CN101577306B - light emitting device - Google Patents

Abstract

A light emitting device is provided that includes a light emitting structure and a magnetic material. The light emitting structure has an excited binding energy of a band gap. The magnetic material is coupled with the light emitting structure to generate a magnetic field in the light emitting structure. The excited binding energy may be above about 25.8meV at room temperature.

Description

light emitting device

technical field

The present disclosure relates generally to a light emitting device, and in particular, to a light emitting device having a magnetic field.

Background technique

A light emitting device (eg, a light emitting diode (LED)) can emit light due to driving a flow of electrons through an active layer of the light emitting diode. However, if the current density is not uniformly distributed throughout the light emitting area, light uniformity is reduced. Still further, in conventional designs, the non-transparent top electrode is usually located at the central region of the light emitting region. In this way, the current density under the top electrode is greater than other areas and more light can be emitted. However, light emitted under the top electrode is blocked because the top electrode is not transparent to light. The top electrodes of conventional LEDs block the light emitted at the central region, which has the highest intensity, resulting in a reduction in output light.

How to improve the light output efficiency of LEDs still requires further development in the technical field.

Contents of the invention

Accordingly, the present disclosure is directed to a light emitting device having a magnetic field in order to at least improve luminous efficiency.

The present disclosure provides a light emitting device, which includes a light emitting structure and a magnetic material. The light emitting structure has an exciting binding energy with a band gap. The magnetic material is coupled with the light emitting structure to generate a magnetic field in the light emitting structure. The excited binding energy can be higher than about 25.8 meV at room temperature.

换句话说，在施加磁场的情况下，发光装置的磁致电阻服从由 $\frac{{\mathrm{\ρ}}_t}{t_t}(1+{{\mathrm{\μ}}_t}^2{B}^2)\≅\frac{{\mathrm{\ρ}}_n}{t_{\mathrm{nI}}}(1+{{\mathrm{\μ}}_n}^2{B}^2)$ 所表示的公式。The present disclosure provides a light emitting device, which includes a light emitting structure and a magnetic material. The light-emitting structure includes a P-type layer, a light-emitting layer, an N-type layer and a transparent conductive layer. The N-type layer has resistivity ρ _n , thickness tn and carrier mobility μ _n , and the transparent conductive layer has resistivity ρ _t , thickness t _t and carrier mobility μ _t . During operation of the light emitting device, current flows in the N-type layer for a depth _tnI through the cross-section of the N-type layer, and the depth _tnI is less than or equal to the thickness _tn . The magnetic material is coupled with the light emitting structure to generate a magnetic field B in the light emitting structure. When the magnetic field B provided by the magnetic material is applied to the light-emitting device, the magnetoresistance of the transparent conductive layer substantially equal to the magnetoresistance of the N-type layer

In other words, in the case of an applied magnetic field, the magnetoresistance of the light-emitting device obeys the $\frac{{\mathrm{\ρ}}_t}{t_t}(1+{{\mathrm{\μ}}_t}^2{B}^2)\≅\frac{{\mathrm{\ρ}}_{\mathrm{no}}}{t_n}(1+{{\mathrm{\μ}}_{\mathrm{no}}}^2{B}^2)$ represented by the formula.

As mentioned above, the magnetic material is integrated into the structure of the light emitting device. In other words, the magnetic field is independently self-supplied into a single light emitting device. A single light emitting device can also be easily packaged into a chip. Therefore, a magnetic field may be applied to the light emitting device in the above-described manner in order to improve luminous efficiency and increase brightness of the light emitting device.

In order to make the foregoing and other features and advantages of the present disclosure more comprehensible, preferred embodiments accompanied by accompanying drawings are described in detail below.

Description of drawings

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments of the disclosure and together with the description serve to explain principles of the disclosure.

FIG. 1 is a structural cross-sectional view illustrating a light emitting device according to one embodiment of the present disclosure.

2 to 5 are cross-sectional views schematically illustrating light emitting devices according to embodiments of the present disclosure, respectively.

6A to 6B are respectively cross-sectional views schematically illustrating a light emitting device according to an embodiment of the present disclosure.

FIG. 7A schematically illustrates distribution curves of wavelength versus photoluminescence (PL) intensity when different powers of laser light are injected into the light emitting device without applying a magnetic field.

FIG. 7B schematically illustrates the distribution curve of wavelength versus PL intensity under different laser powers injected according to the light-emitting device under the condition of applying a magnetic field.

FIG. 8 schematically illustrates a distribution curve of a thickness of a transparent conductive layer (TCL) versus a current distribution uniformity of a conventional light emitting device without applying a magnetic field.

9 to 11 are cross-sectional views schematically illustrating light emitting devices according to embodiments of the present disclosure, respectively.

Fig. 12A schematically illustrates distribution curves of injected current versus forward voltage according to a light emitting device with and without an applied magnetic field, respectively.

Fig. 12B schematically illustrates distribution curves of injection current versus luminous power according to a light emitting device with and without a magnetic field applied, respectively.

Detailed ways

Reference will now be made in detail to the presently preferred embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used throughout the drawings and description to refer to the same or like parts.

Among physical phenomena, the Hall effect is well known, that is, when a current flows through a wire and an external magnetic field is applied transversely, then the path of the current (e.g., electron flow) is also due to the magnetic Lorentz force ( magnetic Lorenz force) F=q*v*B and deflected laterally. This disclosure relates to the consideration of the Hall effect and its implementation into light emitting devices.

FIG. 1 is a structural cross-sectional view illustrating a light emitting device having a magnetic field according to one embodiment of the present disclosure. In FIG. 1, a light emitting diode (LED) is taken as an example. The light emitting diode includes, for example, a bottom electrode 100 , a light emitting structure 102 , and a top electrode 104 . The light-emitting structure is, for example, a light-emitting stacked layer 102, which includes a first doped layer 102a (for example, a P-doped layer), an active layer 102b for emitting light based on the recombination of electrons and holes, and a second doped layer 102c (for example, , N-doped layer). The top electrode 104 may not be located at the center of the light emitting region 108 .

In operation, current flows from the bottom electrode 100 to the top electrode 104 . However, as shown in FIG. 1, if an external magnetic field is applied laterally in a direction (eg, indicated by indicia 106 into the paper), a Lorentz force is generated that deflects and spreads the current. It is permissible to change or modify the conduction type of the electrodes and the direction of the magnetic field according to the actual design, but the concept remains the same. As a result, at the side regions of the light emitting region 180 , current is deflected laterally and can still flow from the bottom electrode 100 to the top electrode 104 . The driving current can more effectively make the active layer 102b emit light.

For the structure illustrated in FIG. 1 , the two electrodes 100 and 104 are at opposite sides of the light emitting stack 102 , and then a magnetic field parallel to the light emitting region 180 is applied, wherein the drive current is deflected inside the light emitting stack 102 . However, when the electrodes are arranged at the same side of the light emitting stack layers, a large horizontal component current is generated, and thus the direction of the magnetic field can be changed.

In addition, a magnetic field applied to a light emitting device (eg, LED) may also improve conversion efficiency for generating light in the light emitting device when quantum effects are considered. The basic mechanism is that the application of a magnetic field can increase the excitation binding energy of the bandgap in the material of the active region, resulting in an enhanced probability of carrier recombination. In more detail, the excitation binding energy between the conduction band and the valence band can be closer to the valence band by means of a magnetic field, and thereby the internal quantum efficiency (internal quantum efficiency) in the material of the light-emitting device can be effectively enhanced , IQE). In general, the improvement in internal quantum efficiency is more pronounced for materials with excitation binding energies higher than the thermovoltage (eg, higher than about 25.8 meV) at room temperature. The light-emitting structure of the light-emitting device contains a semiconductor material with a desired excitation binding energy. In one embodiment, the light emitting structure of the light emitting device may include an inorganic material with an excitation binding energy higher than 25.8 meV. The inorganic material may be a nitride-based material, such as GaN. Other inorganic materials with excitation binding energies higher than 25.8 meV (eg, Si, CdS, BaO, KI, KCl, KBr, RbCl, LiF, and AgCl) can also be used in the light emitting structure. In one embodiment, the light-emitting structure of the light-emitting device may include organic materials with an excitation binding energy higher than 25.8 meV, such as phosphorescent materials, fluorescent materials, and the like. For example, the phosphorescent material can be red, green, blue or dendrimer, and the fluorescent material can be red, green, blue, yellow or white.

The excited binding energy of a semiconductor material will increase as the magnitude of the applied magnetic field increases. In other words, the present disclosure proposes that a magnetic field applied to a light emitting device can additionally increase excitation binding energy, IQE, and carrier recombination, resulting in significantly improved luminous efficiency.

In the case where an external magnetic field is applied to the light emitting device, not only the uniformity of the carrier density of the semiconductor is changed, but also the luminous efficiency is improved. Therefore, for photoelectric conversion, although the amount of injected current remains constant, the light emitting device has higher luminance efficiency.

Note herein that the strength of the external magnetic field applied to the light emitting device may be greater than 0.01 Gauss (G). Furthermore, the magnetic field may be provided by magnets, magnetic films, electromagnets or any other kind of magnetic material, and the number thereof is not limited herein. In addition, the magnetic material may be attached to the light emitting device itself in the form of a magnetic film or a magnetic bulk, depending on its thickness. Note also that the orientation of the magnetic field may be suitably arranged, such as vertically, horizontally or in any direction relative to the light emitting device. The magnetic material can be a ferromagnetic material, such as Rb, Ru, Nd, Fe, Pg, Co, Ni, Mn, Cr, Cu, Cr ₂ , Pt, Sm, Sb, Pt or alloys of the aforementioned materials. The magnetic material can also be a ceramic material, such as oxides of Mn, Fe, Co, Cu, and V; Cr ₂ O ₃ ; CrS; MnS; MnSe; MnTe; fluorides of Mn, Fe, Co, and Ni; Chlorides of Fe, _Co , Ni, and _Cu ; Bromides _of Cu; CrSb _; MnAs; _MnBi ; α-Mn; _x (SO ₄ ) _x Cl ₂ ·6H ₂ O; FeCO ₃ and FeCO ₃ ·2MgCO ₃ . The light emitting device can be inorganic LED or organic LED (OLED), and the light emitting device can also be vertical type, horizontal type, thin film type or flip chip type.

Based on the aforementioned aspects, in practical applications, the light emitting device can be combined with the magnetic material through various methods (eg, epoxy resin, metal bonding, wafer bonding, epitaxial growth embedding and coating). Embodiments of a light emitting device having a magnetic material employing the aforementioned structure are respectively described below. Note that the following examples in which the first conductivity type is P-type and the second conductivity type is N-type are provided for illustrative purposes, and should not be construed as limiting the scope of the present disclosure.

Regarding a standard LED having a horizontal type structure, FIG. 2 is a schematic cross-sectional view illustrating a light emitting device according to an embodiment of the present disclosure. Referring to FIG. 2 , the light emitting device 200 is a horizontal LED, which includes a light emitting structure coupled with a magnetic material. In one embodiment, the light emitting structure is disposed on the magnetic submount 220 through epoxy resin, metal bonding, wafer bonding, epitaxial embedding or coating process. The magnetic substrate 220 is, for example, a ferromagnetic layer having magnetization in a desired direction.

The light emitting structure includes a first electrode 202 , a first doped layer 204 , an active layer 206 , a second doped layer 208 , a second electrode 210 and a substrate 212 . The substrate 212 is mounted on a magnetic substrate 220 . The first doped layer 204 (eg, a P-type doped layer), the active layer 206 and the second doped layer 208 (eg, an N-type doped layer) jointly form a light emitting stack disposed on the substrate 212 . The first electrode 202 is disposed on the first doped layer 204 and electrically connected to the first doped layer 204 . The second electrode 210 is disposed at the same side of the first electrode 202 and is electrically coupled to the second doped layer 208 . Thus, a horizontal type LED structure is formed. The active layer 206 is disposed between the first doped layer 204 and the second doped layer 208 and is capable of generating light when current flows therethrough.

Applying the magnetic field generated by the magnetic substrate 220 to the light emitting structure increases the excitation binding energy of the semiconductor material in the light emitting structure to enhance the overall luminous efficiency of the light emitting device 200 .

FIG. 3 is a schematic cross-sectional view illustrating a light emitting device according to an embodiment of the present disclosure. The same elements shown in FIGS. 2 and 3 are designated by the same reference numerals, and detailed descriptions of the same or similar elements are omitted below.

As shown in FIG. 3 , the structural components of the light emitting device 300 are generally similar to those of the light emitting device 200 shown in FIG. 2 , except for the deployment of the magnetic material. In one embodiment, to implement the magnetic source, a packaging structure (eg, flip-chip packaging) may be used to couple the magnetic material with the light emitting structure. The first electrode 202 and the second electrode 210 of the light emitting structure may be mounted on the magnetic substrate 320 . In one embodiment, the light emitting structure can be packaged on the magnetic substrate 320 via the bonding structures 302 and 304 . The bonding structures 302 and 304 are, for example, bonding bumps. In another embodiment, the light emitting structure may be directly bonded to the magnetic substrate 320 without any bonding structure. That is, the first electrode 202 and the second electrode 210 may be directly mounted on the surface of the magnetic substrate 320 . As a result, the magnetic substrate 320 can generate a magnetic field into the light emitting device 300 , and the excitation binding energy of the semiconductor material in the light emitting structure is thus increased to enhance the light emitting efficiency of the light emitting device 300 .

FIG. 4 is a schematic cross-sectional view illustrating a light emitting device according to an embodiment of the present disclosure.

Regarding a thin film LED having a vertical type structure, FIG. 4 is a schematic cross-sectional view illustrating a light emitting device according to one embodiment of the present disclosure. Referring to FIG. 4 , in this embodiment, the light emitting device 400 is a vertical LED, which includes a light emitting structure and a magnetic substrate 420 . The light emitting structure is disposed on the magnetic substrate 420 via epoxy, metal bonding, wafer bonding, epitaxial embedding or coating process.

The light emitting structure includes a second electrode 402 , a second doped layer 404 , an active layer 406 , a first doped layer 408 and a first electrode 410 from top to bottom. The magnetic substrate 420 serves as a substrate of the light emitting structure. The second doped layer 404 , the active layer 406 and the first doped layer 408 form a light emitting stack layer, which is disposed on the magnetic substrate 420 . The second electrode 402 is disposed on and electrically connected to the second doped layer 404 . The first electrode 410 is disposed between the first doped layer 408 and the magnetic substrate 420 and is electrically connected to the first doped layer 408 . Thus, a vertical type LED structure is formed. The active layer 406 is disposed between the second doped layer 404 and the first doped layer 408 and is capable of generating light when current flows therethrough.

Likewise, the magnetic field induced by the magnetic substrate 420 creates a light-emitting structure, so that the excitation binding energy of the semiconductor material in the light-emitting structure increases to enhance the overall light-emitting efficiency of the light-emitting device 400 .

FIG. 5 is a cross-sectional view schematically illustrating a light emitting device according to an embodiment of the present disclosure. Light emitting device 500 includes a light emitting structure coupled with an embedded magnetic material. Referring to FIG. 5 , the magnetic layer 520 may be formed between the substrate 512 and the light emitting structure 514 based on an epitaxial laterally overgrown (ELOG) technique. In an embodiment, the magnetic layer 520 may be formed on the substrate 512 and then patterned into a desired pattern, such as stripes or blocks. Thereafter, the lower semiconductor layer of the light emitting structure 514 may be grown through an ELOG process. The magnetic layer 520 embedded in the semiconductor material provides a magnetic field to the light emitting device 500 for enhancing its excitation binding energy. Therefore, the luminous efficiency of the light emitting device 500 is effectively improved by applying a magnetic field.

6A to 6B are respectively cross-sectional views schematically illustrating a light emitting device according to an embodiment of the present disclosure. The same elements shown in FIGS. 6A and 6B are designated by the same reference numerals, and detailed descriptions of the same or similar elements are omitted below.

Referring to FIG. 6A , a light emitting device 600 includes a light emitting structure coupled with a magnetic layer 620 . In one embodiment, the light emitting structure is disposed on the magnetic layer 620 through epoxy, metal bonding, wafer bonding, epitaxial embedding or coating process.

The light-emitting structure is, for example, a stacked structure of an organic electroluminescent device (OLED), which includes a substrate 602, an anode layer 604, a hole transporting layer (hole transporting layer, HTL) 606, an electroluminescent layer 608, electron An electron transporting layer (ETL) 610 and a cathode layer 612 . Substrate 602 is disposed on magnetic layer 620 , and anode layer 604 is disposed on a surface of substrate 602 . A hole transport layer (HTL) 606, an electroluminescent layer 608, and an electron transport layer (ETL) 610 are, for example, stacked between the anode layer 604 and the cathode layer 612, wherein the electroluminescent layer 608 is disposed on the hole transport layer (HTL) 606 and the electron transport layer (ETL) 610. The substrate 602 may be a transparent substrate, such as a glass substrate. Anode layer 604 is typically composed of a metal or a transparent conductive material such as indium tin oxide (ITO), silicon, tin oxide, gold, silver, platinum, or copper. In one embodiment, the anode layer 604 may be a transparent conductive layer including indium tin oxide (ITO) or silicon. The hole transport layer (HTL) 606, the electroluminescent layer 608, and the electron transport layer (ETL) 610 may each be composed of an organic material. Cathode layer 612 may comprise a metal or a transparent conductive material such as aluminum, silver or indium tin oxide (ITO). Note, however, that the present disclosure is not limited to the above materials. Other suitable materials may also be used for the purposes of this disclosure and are understood to be within the scope of this disclosure.

In one embodiment, the light emitting device 600 may further include a hole injection layer (HIL) 614 and an electron injection layer (EIL) 616 in the stack structure. A hole injection layer (HIL) 614 is disposed between the hole transport layer (HTL) 606 and the anode layer 604 . Electron injection layer (EIL) 616 is disposed between cathode layer 612 and electron transport layer (ETL) 610 . Please note that the organic light emitting structure can also be implemented by including at least one of the aforementioned layers between the anode layer 604 and the cathode layer 612 , and it is not construed as limiting the scope of the present disclosure.

When an offset voltage is applied between the anode layer 604 and the cathode layer 612, electrons are injected from the cathode layer 612 into the electron transport layer (ETL) 610 and transported to the electroluminescent layer 608, while holes are transferred from The anode layer 604 is injected into a hole transport layer (HTL) 606 . In addition, the injected holes are transported to the electroluminescent layer 608, where the electrons and holes recombine to generate excitons and produce a luminescent effect. Applying the magnetic field generated by the magnetic layer 620 to the light-emitting structure increases the excitation binding energy of materials in the light-emitting structure to enhance the overall luminous efficiency of the light-emitting device 600 .

The organic light emitting device may have another configuration. As shown in FIG. 6B, the structural components of light emitting device 600a are generally similar to those of light emitting device 600 shown in FIG. 6A, except for the deployment of magnetic layer 620a. In one embodiment, a packaging structure (eg, flip-chip packaging) may be used to couple the magnetic layer 620 a with the light emitting structure. In other words, the stacked light emitting structure can be packaged with the magnetic layer 620a by mounting the cathode layer 612 to the magnetic layer 620a to form a flip chip structure. Similarly, the magnetic field generated by the magnetic layer 620a can increase the excitation binding energy of materials in the light emitting structure, thereby enhancing the overall luminous efficiency of the light emitting device 600a.

The following examples are provided to demonstrate that light-emitting devices of materials with excitation binding energies higher than 25.8 meV have better improvements in IQE and luminous efficiency with the application of a magnetic field. These examples are provided only to illustrate the effect on photoluminescence (PL) produced by the deployment of magnetic materials in the present disclosure, and are not intended to limit the scope of the present disclosure.

Example I

FIG. 7A schematically illustrates the distribution curves of wavelength versus PL intensity when different powers of laser light are injected according to the light-emitting device without applying a magnetic field. FIG. 7B schematically illustrates the distribution curve of wavelength versus PL intensity under different laser powers injected according to the light-emitting device under the condition of applying a magnetic field.

A GaN chip with an excitation binding energy higher than 25.8 meV was used as a sample. Lasers of different intensities were fired into the GaN chip under the same conditions except for the applied magnetic field, and then the photoluminescence generated by the material of the chip was collected and measured. Lasers with different powers of 6 mW, 8 mW, 10 mW and 12 mW were driven into GaN chips with no magnetic field applied or with magnetic field applied, and the test results are shown in FIGS. 7A and 7B , respectively.

As can be seen from the curves, the measured PL intensity in the light emitting device with an applied magnetic field (as shown in FIG. 7B ) is higher than the measured PL intensity in the light emitting device without an applied magnetic field (as shown in FIG. 7A ). Show). Therefore, it turns out that the magnetic field can significantly improve the PL intensity and thereby increase the luminous efficiency. Specifically, in injecting a laser with the same power into the device, as shown by the curves representing 12 mW in FIG. 7A and FIG. An improvement of about 27% is achieved. In summary, the luminous efficiency of light-emitting devices comprising materials with excitation binding energies higher than 25.8 meV can be significantly improved by applying a magnetic field. Therefore, device performance can be effectively promoted.

Regardless of the above IQE, in the field of transparent conductive layers (TCLs) that are further disposed in light-emitting devices to enhance their current uniformity, several aspects of transparent conductive layers should be taken into consideration. A transparent conductive layer may be disposed on the surface of the P-type layer. In addition to the high transmittance of the transparent conductive layer, the impedance matching between the transparent conductive layer and the N-type layer is also important, so as to achieve a better current crowding effect.

In the case where the light-emitting device comprises a transparent conductive layer, the realization of impedance matching between the transparent conductive layer and the N-type layer may depend on various parameters, such as the resistivity ρ _t , thickness t _t and carrier mobility of the transparent conductive layer rate μ _t , and the resistivity ρ _n and carrier mobility μ _n of the N-type layer. Please note that during the operation of the light-emitting device, the current only flows through a portion of the N-type layer close to the interface between the N-type layer and the active layer (ie, the light-emitting layer). Therefore, the depth of the current path in the cross-section of the N-type layer represented by t _nI can also affect the realization of impedance matching, wherein the depth of the current path t _nI is less than or equal to the overall thickness t _n of the N-type layer.

表示。大体上，透明导电层的原始电阻不等于N型层的原始电阻

为了实现在发光装置中获得电流的最大均匀分布面积，需要透明导电层与N型层之间的阻抗匹配，其指出 $\frac{{\mathrm{\ρ}}_t}{t_t}\≅\frac{{\mathrm{\ρ}}_n}{t_{\mathrm{nI}}}.$ When the light-emitting device is operated without a magnetic field, the original resistance of the transparent conductive layer is given by Represented, and the original resistance of the N-type layer is given by

express. In general, the original resistance of the transparent conductive layer Not equal to the original resistance of the N-type layer

In order to obtain the maximum uniform distribution area of current in a light-emitting device, impedance matching between the transparent conductive layer and the N-type layer is required, which states $\frac{{\mathrm{\ρ}}_t}{t_t}\≅\frac{{\mathrm{\ρ}}_{\mathrm{no}}}{t_n}.$

时，电流分布均匀度等于1，其指示电流的最大均匀分布面积。然而，电流分布均匀度归因于Ni/Au的厚度t_t的微小变化而急剧下降。也就是说，所述工艺中厚度的容许误差(tolerance)过小以致不能在实际应用中加以实行。因此，仅通过调整常规发光装置的透明导电层的厚度或N型层的厚度不可能实现上述阻抗匹配。FIG. 8 schematically illustrates distribution curves of the thickness of the TCL versus the current distribution uniformity of a conventional light emitting device without applying a magnetic field. As shown in FIG. 8, an alloy of nickel and gold (ie, Ni/Au) serves as a transparent conductive material in a light emitting device. When the thickness t _t of the Ni/Au layer is about 80

When , the current distribution uniformity is equal to 1, which indicates the maximum uniform distribution area of the current. However, the current distribution uniformity drops sharply due to the slight variation in the thickness _t of Ni/Au. That is, the tolerance of thickness in the process is too small to be practical in practical applications. Therefore, it is impossible to achieve the above-mentioned impedance matching only by adjusting the thickness of the transparent conductive layer or the thickness of the N-type layer of the conventional light emitting device.

表示，且N型层的磁致电阻由

表示。当透明导电层的磁致电阻

实质上等于N型层的磁致电阻时，可在施加磁场的情况下实现阻抗匹配，即 $\frac{{\mathrm{\ρ}}_t}{t_t}(1+{{\mathrm{\μ}}_t}^2{B}^2)\≅\frac{{\mathrm{\ρ}}_n}{t_{\mathrm{nI}}}(1+{{\mathrm{\μ}}_n}^2{B}^2).$ 在一实施例中，透明导电层的磁致电阻和N型层的磁致电阻的约等范围(approximate equality range)可通过方程式 $\left|\frac{\frac{{\mathrm{\ρ}}_t}{t_t}(1+{{\mathrm{\μ}}_t}^2{B}^2)-\frac{{\mathrm{\ρ}}_n}{t_{\mathrm{nI}}}(1+{{\mathrm{\μ}}_n}^2{B}^2)}{\frac{{\mathrm{\ρ}}_t}{t_t}(1+{{\mathrm{\μ}}_t}^2{B}^2)+\frac{{\mathrm{\ρ}}_n}{t_{\mathrm{nI}}}(1+{{\mathrm{\μ}}_n}^2{B}^2)}\right|\≤0.2$ 界定。However, the magnetoresistance effect can be applied to facilitate overall equivalent resistance matching in light emitting devices. The magnetoresistance R _b increases with an applied magnetic field B and obeys the equation expressed by R _b (B)=R ₀ (1+μ ² B ² ), where R ₀ represents the pristine resistance, and μ represents the carrier mobility of the material. When the magnetic field B provided by the magnetic material is applied to the light-emitting device of the present disclosure, the magnetoresistance of the transparent conductive layer is determined by

Represented, and the magnetoresistance of the N-type layer is given by

express. When the magnetoresistance of the transparent conductive layer

substantially equal to the magnetoresistance of the N-type layer When , impedance matching can be achieved under the condition of applying a magnetic field, that is, $\frac{{\mathrm{\ρ}}_t}{t_t}(1+{{\mathrm{\μ}}_t}^2{B}^2)\≅\frac{{\mathrm{\ρ}}_{\mathrm{no}}}{t_n}(1+{{\mathrm{\μ}}_{\mathrm{no}}}^2{B}^2).$ In one embodiment, the magnetoresistance of the transparent conductive layer and the magnetoresistance of the N-type layer are approximately equal (approximate equality range) by the equation $\left|\frac{\frac{{\mathrm{\ρ}}_t}{t_t}(1+{{\mathrm{\μ}}_t}^2{B}^2)-\frac{{\mathrm{\ρ}}_{\mathrm{no}}}{t_n}(1+{{\mathrm{\μ}}_{\mathrm{no}}}^2{B}^2)}{\frac{{\mathrm{\ρ}}_t}{t_t}(1+{{\mathrm{\μ}}_t}^2{B}^2)+\frac{{\mathrm{\ρ}}_{\mathrm{no}}}{t_n}(1+{{\mathrm{\μ}}_{\mathrm{no}}}^2{B}^2)}\right|\≤0.2$ defined.

In more detail, the carrier mobility μ _n of the N-type layer is generally greater than the carrier mobility μ _t of the transparent conducting layer due to intrinsic material properties. When the original resistance is constant at both sides of the impedance matching equation, the increase in magnetoresistance of the N-type layer is higher than that of the transparent conductive layer after a constant magnetic field is applied to the light emitting device. Therefore, in one embodiment, when no magnetic field is applied to the light emitting device, the value of the original resistance defining the transparent conductive layer is higher than the value of the original resistance of the N-type layer, that is, $\frac{{\mathrm{\ρ}}_t}{t_t}\&Greater\; Equal;\frac{{\mathrm{\ρ}}_{\mathrm{no}}}{t_n}.$ In one embodiment, the relationship between the original resistance of the transparent conductive layer and the N-type layer can be obtained by the equation $\frac{|\frac{{\mathrm{\ρ}}_t}{t_t}-\frac{{\mathrm{\ρ}}_{\mathrm{no}}}{t_n}|}{|\frac{{\mathrm{\ρ}}_t}{t_t}+\frac{{\mathrm{\ρ}}_{\mathrm{no}}}{t_n}|}\≤0.5$ To represent. In the foregoing aspect, in the case where a magnetic field is applied to the light-emitting device in the present disclosure, the optimum impedance matching between the transparent conductive layer and the N-type layer can be achieved by finely adjusting the respective thicknesses of the transparent conductive layer and the N-type layer. good condition. Compared with a conventional light emitting device having an extremely low thickness tolerance, since the application of a magnetic field can easily control the magnetoresistance of the transparent conductive layer to be substantially equal to that of the N-type layer, so that the light emission can be significantly improved. efficiency.

到150

的范围内。当透明导电层由半导体(例如，氧化铟锡(ITO)和氧化锌(ZnO))组成时，厚度t_t可在1000到5000

的范围内。在一实施例中，N型层的材料可为半导体，例如，GaAs、氮化物基(nitride-based)材料、铟(In-based)基材料、铝基(Al-based)材料、镓基(Ga-based)材料、硅基(Si-based)材料或铅基(Pb-based)材料。磁场B例如大于0.01高斯(G)。In one embodiment, the material of the transparent conductive layer may be metal or semiconductor. When the transparent conductive layer is composed of metal (for example, Ni/Au), the thickness t _t can be in the range of 50

to 150

In the range. When the transparent conductive layer is composed of a semiconductor (for example, indium tin oxide (ITO) and zinc oxide (ZnO)), the thickness t _t can be in the range of 1000 to 5000

In the range. In one embodiment, the material of the N-type layer can be a semiconductor, for example, GaAs, a nitride-based material, an indium (In-based) material, an aluminum-based (Al-based) material, a gallium-based ( Ga-based) material, silicon-based (Si-based) material or lead-based (Pb-based) material. The magnetic field B is, for example, greater than 0.01 Gauss (G).

Several practical applications of the aforementioned light emitting device structures according to the present disclosure are provided below. It should be understood that the following structure intends to explain the composition of the thickness relationship between the transparent conductive layer and the N-type layer, thereby enabling those skilled in the art to practice the present disclosure, rather than limiting the scope of the present disclosure. Those skilled in the art will appreciate that other elements may be arranged and formed in ways not shown in the illustrated embodiments according to known knowledge in the art.

FIG. 9 is a schematic cross-sectional view illustrating a light emitting device according to an embodiment of the present disclosure. Referring to FIG. 9, the light emitting device 200a is a horizontal LED, which includes a light emitting structure coupled with a magnetic material. The structure of the light emitting device 200 a is roughly similar to that of the light emitting device 200 shown in FIG. 2 , except for the deployment of the transparent conductive layer 230 . A transparent conductive layer 230 is further disposed over the first doped layer 204 in order to enhance the effect of current crowding. The transparent conductive layer 230 has a thickness t _t , and the second doped layer 208 (ie, N-type layer) has a thickness t _n . The thickness t _t and the thickness t _n can be adjusted according to different materials of the transparent conductive layer 230 and the second doped layer 208, so that the magnetoresistance of the transparent conductive layer 230 can be easily controlled to be substantially is equal to the magnetoresistance of the second doped layer 208 . Therefore, the luminous efficiency of the light emitting device 200 a can be improved by adjusting the thickness t _t and the thickness t _n by using the applied magnetic field to achieve impedance matching.

FIG. 10 is a schematic cross-sectional view illustrating a light emitting device according to an embodiment of the present disclosure. The same elements shown in FIGS. 9 and 10 are designated by the same reference numerals, and detailed descriptions of the same or similar elements are omitted below.

Referring to FIG. 10 , the structural components of the light emitting device 300 a are substantially similar to those of the light emitting device 200 a shown in FIG. 9 , except for the deployment of the magnetic layer 320 . In one embodiment, a packaging structure (eg, flip-chip packaging) may be used to couple the magnetic layer 320 with the light emitting structure. In other words, the first electrode 202 and the second electrode 210 of the light emitting structure may be mounted on the magnetic substrate 320 . The magnetic substrate 320 may also generate a magnetic field into the light emitting device 300a, thereby improving light emitting efficiency due to the realization of impedance matching.

FIG. 11 is a schematic cross-sectional view illustrating a light emitting device according to an embodiment of the present disclosure.

Regarding thin film LEDs with a vertical structure, as shown in FIG. 4 , a light emitting device 400 a includes a light emitting structure and a magnetic substrate 420 . The structure of the light emitting device 400 a is roughly similar to that of the light emitting device 400 shown in FIG. 4 , except for the deployment of the transparent conductive layer 430 . A transparent conductive layer 430 is further disposed over the second doped layer 404 in order to enhance the effect of current crowding. The transparent conductive layer 430 has a thickness t _t , and the second doped layer 404 (ie, N-type layer) has a thickness t _n . The thickness t _t and the thickness t _n can be adjusted according to different materials of the transparent conductive layer 430 and the second doped layer 404 , so as to achieve impedance matching. Therefore, the luminous efficiency of the light emitting device 400a can be improved by utilizing the applied magnetic field and adjusting the thickness t _t and the thickness t _n .

In addition, when the light emitting device is an organic light emitting device, the anode may be composed of a transparent conductive layer. Taking the light emitting devices 600 and 600a illustrated in FIGS. 6A and 6B , respectively, as an example, the anode layer 604 has a thickness t _t , and an electron transport layer (ETL) 610 and an electron injection layer (EIL) 616 (ie, N-type layers) collectively have a thickness t _n . The thickness t _t and the thickness t _n can be adjusted according to different materials of the anode layer 604 and the electron transport layer (ETL) 610 and the electron injection layer (EIL) 616, respectively, so that the magnetic properties of the transparent conductive layer can be easily controlled under the condition of applying a magnetic field. The resulting resistance is substantially equal to the magnetoresistance of the N-type layer. Therefore, the luminous efficiency of the light emitting device 600 or 600a can be improved by adjusting the thickness t _t and the thickness t _n by using the applied magnetic field to achieve impedance matching.

In one embodiment, when the light emitting device 600 or 600a includes a hole transport layer (HTL) 606, an electroluminescent layer 608 and an electron transport layer (ETL) 610 stacked between the anode layer 604 and the cathode layer 612 without disposing When the hole injection layer (HIL) 614 and the electron injection layer (EIL) 616 are used, the thickness t _n of the N-type layer may refer to the thickness of the electron transport layer (ETL) 610 alone. The organic light emitting device can also be implemented by including at least one of the foregoing layers between the anode layer 604 and the cathode layer 612, and it is not construed as limiting the scope of the present disclosure. Thus, the thicknesses t _t and t _n can be modified based on the respective deployment of the transparent conductive layer and the N-type layer.

The following examples are provided to demonstrate that a light emitting device has a better improvement in luminous efficiency by well controlling the thickness t _t and t _n under the application of a magnetic field. These examples are provided merely to illustrate the effect on forward voltage and optical output power resulting from the deployment of magnetic material in the present disclosure, and are not intended to limit the scope of the present disclosure.

Example II

Fig. 12A schematically illustrates distribution curves of injected current versus forward voltage according to a light emitting device with and without an applied magnetic field, respectively. Fig. 12B schematically illustrates distribution curves of injection current versus luminous power according to a light emitting device with and without a magnetic field applied, respectively.

，而GaN(N型层)的厚度t_n为约28000。其后，在施加和不施加磁场的情况下测量GaN LED的正向电压和发光功率，且分别在图12A和图12B中展示测试结果。A GaN LED was used as a sample, and a transparent conductive material was formed on the surface of the GaN chip. An alloy of nickel and gold (ie, Ni/Au) acts as a transparent conductive material formed on the surface of the GaN LED. The thickness _t of the Ni/Au layer is about 90

, while the thickness t _n of GaN (N-type layer) is about 28000 . Thereafter, the forward voltage and luminous power of the GaN LED were measured with and without a magnetic field applied, and the test results are shown in FIGS. 12A and 12B , respectively.

As shown in FIG. 12A, curve 1201 represents the forward voltage of the GaN LED measured without applying a magnetic field to the GaN LED, while curve 1202 represents the measured forward voltage of the GaN LED under a magnetic field of about 0.3 Tesla (T). Forward Voltage. As can be observed in FIG. 12A , the distribution of curve 1202 is lower than that of curve 1201 . All in all, the forward voltage of a GaN LED can be dropped by more than 5% with the help of an applied magnetic field.

As shown in FIG. 12B, curve 1203 represents the light output power of the GaN LED measured without applying a magnetic field to the GaN LED, while curve 1204 represents the light output power of the GaN LED measured under a magnetic field of about 0.3 Tesla (T). power. The distribution of curve 1204 is much higher than that of curve 1203 . More specifically, the luminous efficiency of curve 1204 is increased by more than 20% compared to the luminous efficiency of curve 1203, thereby indicating that the luminous efficiency of GaN LEDs can be significantly improved by applying a magnetic field.

In view of the above, improvements in IQE and carrier recombination can be increased with increased excitation binding energy of semiconductor materials in light emitting devices. Therefore, the luminous efficiency of the light emitting device is significantly enhanced.

In addition, the magnetoresistances of the transparent conductive layer and the N-type layer can be made substantially equal to each other by easily adjusting the respective thicknesses of the transparent conductive layer and the N-type layer under application of a magnetic field. Since the impedance matching between the transparent conductive layer and the N-type layer can be obtained by applying a magnetic field, the maximum uniform distribution area of current can be obtained in the light emitting device. Therefore, the current uniformity and luminous efficiency of the light emitting device can be effectively improved.

Furthermore, a magnetic field can be applied to the light emitting device in the manner described above, so as to improve the luminous efficiency and increase the brightness of the light emitting device.

It will be apparent to those skilled in the art that various modifications and changes can be made in the structure of the present disclosure without departing from the scope or spirit of the present disclosure. In view of the foregoing, it is intended that the present disclosure cover modifications and variations of this disclosure provided they come within the scope of the following claims and their equivalents.

Claims (33)

1. light-emitting device comprises:

Ray structure, it has the binding energy that excites of band gap; And

Magnetic material, itself and the coupling of said ray structure are to produce magnetic field in said ray structure, and said magnetic field is greater than 0.01 Gauss (G).

2. light-emitting device according to claim 1 is characterized in that the said binding energy that excites at room temperature is higher than 25.8meV.

3. light-emitting device according to claim 1 is characterized in that said magnetic material is magnetic film or magnetic block.

4. light-emitting device according to claim 1 is characterized in that said ray structure comprises semi-conducting material.

5. light-emitting device according to claim 4 is characterized in that said ray structure comprises nitride based materials.

6. light-emitting device according to claim 1 is characterized in that said ray structure comprises inorganic material.

7. light-emitting device according to claim 6 is characterized in that said ray structure further comprises:

First doped layer;

Second doped layer; And

Active layer, it is placed between said first doped layer and said second doped layer.

8. light-emitting device according to claim 7 is characterized in that said ray structure further comprises:

First electrode, it is coupled to said first doped layer; And

Second electrode, it is coupled to said second doped layer.

9. light-emitting device according to claim 1 is characterized in that said ray structure comprises organic material.

10. light-emitting device according to claim 9 is characterized in that said ray structure further comprises:

Electron supplying layer;

Hole transporting layer; And

Electroluminescence layer, it is placed between said hole transporting layer and the said electron supplying layer.

11. a light-emitting device comprises:

Ray structure, it comprises:

P type layer;

Transparency conducting layer, it has the electricalresistivity _t, thickness t _tWith carrier mobility μ _tAnd

N type layer, it has the electricalresistivity _n, thickness t _nWith carrier mobility μ _n, and magnetic material, itself and the coupling of said ray structure are to produce magnetic field B, the magnetoresistance of wherein said transparency conducting layer in said ray structure Equal the magnetoresistance of said N type layer in fact

12. light-emitting device according to claim 11 is characterized in that

$\left|\frac{\frac{{\mathrm{\ρ}}_t}{t_t}(1+{{\mathrm{\μ}}_t}^2{B}^2)-\frac{{\mathrm{\ρ}}_n}{t_{n1}}(1+{{\mathrm{\μ}}_n}^2{B}^2)}{\frac{{\mathrm{\ρ}}_t}{t_t}(1+{{\mathrm{\μ}}_t}^2{B}^2)+\frac{{\mathrm{\ρ}}_n}{t_{n1}}(1+{{\mathrm{\μ}}_n}^2{B}^2)}\right|\≤0.2.$

13. light-emitting device according to claim 11 is characterized in that the original resistance

of the original resistance

of said transparency conducting layer more than or equal to said N type layer

14. light-emitting device according to claim 11 is characterized in that

15. light-emitting device according to claim 11 is characterized in that said transparency conducting layer comprises metal.

16. light-emitting device according to claim 15 is characterized in that said transparency conducting layer comprises Ni/Au.

17. light-emitting device according to claim 15 is characterized in that said thickness t _tBe

Arrive Scope in.

18. light-emitting device according to claim 11 is characterized in that said transparency conducting layer comprises semiconductor.

19. light-emitting device according to claim 18 is characterized in that said transparency conducting layer comprises tin indium oxide and zinc oxide.

20. light-emitting device according to claim 18 is characterized in that said thickness t _tBe 1000

Arrive

Scope in.

21. light-emitting device according to claim 11 is characterized in that said N type layer comprises semiconductor.

22. light-emitting device according to claim 21 is characterized in that said N type layer is GaAs, nitride based materials, indium sill, alumina-base material, gallium sill, silica-base material or lead base material.

23. light-emitting device according to claim 11 is characterized in that said transparency conducting layer is placed on the surface of said P type layer.

24. light-emitting device according to claim 11 is characterized in that said magnetic material is magnetic film or magnetic block.

25. light-emitting device according to claim 11 is characterized in that said magnetic field B is greater than 0.01 Gauss (G).

26. light-emitting device according to claim 11 is characterized in that said ray structure comprises inorganic material.

27. light-emitting device according to claim 26 further comprises:

Active layer, it is placed between said N type layer and the said P type layer;

First electrode, it is coupled to said P type layer; And

Second electrode, it is coupled to said N type layer.

28. light-emitting device according to claim 11 is characterized in that said ray structure comprises organic material.

29. light-emitting device according to claim 28 further comprises:

Electroluminescence layer, it is placed between said P type layer and the said N type layer; And

Negative electrode, it is placed on the said N type layer.

30. light-emitting device according to claim 29 is characterized in that said N type layer comprises electron supplying layer.

31. light-emitting device according to claim 30 is characterized in that said N type layer further comprises the electron injecting layer that is placed between electron supplying layer and the said negative electrode.

32. light-emitting device according to claim 29 is characterized in that said P type layer comprises the hole transporting layer that is placed between said transparency conducting layer and the said N type layer.

33. light-emitting device according to claim 32 is characterized in that said P type layer further comprises the hole injection layer that is placed between hole transporting layer and the said transparency conducting layer.

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