CN110459655A - A quantum barrier doped deep ultraviolet LED and its preparation method - Google Patents

Abstract

The invention discloses deep ultraviolet LED and preparation method that a kind of quantum builds doping, the deep ultraviolet LED that the quantum builds doping includes Sapphire Substrate, N-type AlGaN contact layer, mqw active layer, p-type AlGaN carrier transport and p-type GaN contact layer, N-type AlGaN contact layer is set gradually in the Sapphire Substrate, mqw active layer, p-type AlGaN carrier transport and p-type GaN contact layer；The mqw active layer is stacked gradually by the quantum lamination in 6 periods and is constituted, and the quantum lamination includes quantum barrier layer and quantum well layer, and the quantum barrier layer is the Al of 12nm_0.55Ga_0.45N quantum is built, and the quantum barrier layer Si doping concentration is 5 × 10¹⁸~1 × 10¹⁹.The present invention builds the effect that polarization self-shileding is realized in doping using quantum, the carrier Wave function overlap rate inside Quantum Well is improved, to improve the light power of deep ultraviolet LED.

Description

A quantum barrier doped deep ultraviolet LED and its preparation method

technical field

The invention relates to the field of optoelectronic technology, in particular to a quantum barrier doped deep ultraviolet LED and a preparation method.

Background technique

Currently, AlGaN-based deep-UV LEDs (i.e., UV wavelength λ<300nm) have attracted the attention of many scientists due to their wide range of potential applications, such as disinfection, air and water purification, biochemical detection, and optical communication. However, the low external quantum efficiency of deep ultraviolet LEDs still cannot meet the current application requirements, which is mainly limited by its low internal quantum efficiency and light extraction efficiency.

Due to the strong asymmetry in the AlGaN material, there is a strong spontaneous polarization and piezoelectric polarization inside it, and the generated polarization electric field makes the wave function of the hole carriers and electron carriers in the quantum well Separation reduces the probability of photons generated by their mutual coupling, thus seriously affecting the internal quantum efficiency and light extraction rate of the LED. Based on the conventional deep-ultraviolet LED chip epitaxial structure design, in order to improve the coverage of the quantum well wave function of the deep-ultraviolet LED, a new design of the structure of the deep-ultraviolet LED is required to solve the problems existing in the prior art.

Contents of the invention

The purpose of the present invention is to provide a quantum barrier doped deep ultraviolet LED and a preparation method, which are used to solve the problem in the prior art that the polarization electric field of AlGaN material limits the internal quantum efficiency of the ultraviolet LED.

In order to solve the above technical problems, the present invention provides a first solution: a quantum barrier doped deep ultraviolet LED, including a sapphire substrate, an N-type AlGaN contact layer, a quantum well active layer, a P-type AlGaN carrier input The transport layer and the P-type GaN contact layer, the N-type AlGaN contact layer, the quantum well active layer, the P-type AlGaN carrier transport layer and the P-type GaN contact layer are arranged successively on the sapphire substrate; the quantum well active layer consists of 6 A period of quantum _stacks are _stacked in sequence. ^The quantum stack includes a quantum barrier layer and a quantum well layer. 1×10 ¹⁹ .

Preferably, the quantum well layer is a 3nm Al _0.45 Ga _0.55 N quantum well, and the quantum well layer is not doped.

Preferably, the thickness of the N-type AlGaN contact layer is 2-3 μm, and the Si doping concentration is 5×10 ¹⁸ to 1×10 ¹⁹ .

Preferably, the thickness of the P-type AlGaN carrier transport layer is 25 nm, and the Mg doping concentration is 1×10 ¹⁹ -3×10 ¹⁹ .

Preferably, the thickness of the P-type GaN contact layer is 300 nm, and the doping concentration of Mg is 1×10 ¹⁹ -5×10 ¹⁹ .

In order to solve the above technical problems, the present invention provides a second solution: a quantum barrier-doped deep-ultraviolet LED preparation method, the specific steps of which are sequentially depositing an N-type AlGaN contact layer on a sapphire substrate by metal-organic chemical vapor deposition , quantum well active layer, P-type AlGaN carrier transport layer and P-type GaN contact layer; quantum barrier doped deep ultraviolet LED preparation method is used to prepare any quantum barrier doped deep ultraviolet LED in the aforementioned first solution UV LEDs.

Preferably, when preparing quantum barrier-doped deep ultraviolet LEDs, the Ga source used is trimethylgallium TMGa, the Al source is trimethylgallium TMAl, the nitrogen source is ammonia NH ₃ , and the carrier gas is hydrogen H ₂ , The doping sources of N-type and P-type are silane SiH ₄ and magnesiumocene Cp ₂ Mg respectively.

Preferably, the reaction temperature when depositing the N-type AlGaN contact layer is 1050-1080°C; the reaction temperature when depositing the quantum well active layer is 1050-1080°C; the reaction temperature when depositing the P-type AlGaN carrier transport layer is 1050-1080°C; the reaction temperature when depositing the P-type GaN contact layer is 950-1000°C.

The beneficial effects of the present invention are: different from the situation of the prior art, the present invention provides a quantum barrier doped deep ultraviolet LED and a preparation method, utilizes quantum barrier doping to realize the polarization self-shielding effect, and improves the internal density of the quantum well. The carrier wave function overlap rate, thereby improving the light output power of the deep ultraviolet LED.

Description of drawings

Fig. 1 is a schematic structural view of an embodiment of a quantum barrier-doped deep ultraviolet LED in the present invention;

Fig. 2 is a schematic structural view of the quantum well active layer in an embodiment of the deep ultraviolet LED doped with quantum barriers in the present invention;

Fig. 3 is a principle schematic diagram of an embodiment of a deep ultraviolet LED doped with a quantum barrier in the present invention;

Fig. 4 is a graph showing the relationship between the doping concentration of the quantum barrier layer, the wave function coverage and the light output power in an embodiment of the deep ultraviolet LED doped with quantum barriers in the present invention;

Fig. 5 is a graph showing the relationship between the hole carrier concentration of the quantum well layer and the doping concentration of the quantum barrier layer in an embodiment of the deep ultraviolet LED doped with quantum barriers in the present invention;

FIG. 6 is a graph showing the relationship between the luminous power and the doping concentration of the quantum barrier layer in an embodiment of the deep ultraviolet LED doped with quantum barriers in the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

For the first solution provided by the present invention, please refer to Fig. 1 and Fig. 2, Fig. 1 is a schematic structural diagram of an embodiment of a deep ultraviolet LED doped with a quantum barrier in the present invention, and Fig. 2 is a diagram of a deep ultraviolet LED doped with a quantum barrier in the present invention Schematic diagram of the structure of the quantum well active layer in an embodiment of the deep ultraviolet LED. The deep ultraviolet LED doped with quantum barriers in the present invention comprises a sapphire substrate 1, an N-type AlGaN contact layer 2, a quantum well active layer 3, a P-type AlGaN carrier transport layer 4 and a P-type GaN contact layer 5, An N-type AlGaN contact layer, a quantum well active layer, a P-type AlGaN carrier transport layer and a P-type GaN contact layer are sequentially arranged on the sapphire substrate 1 .

Specifically, the structure and components of each layer of the quantum barrier-doped deep ultraviolet LED are described in detail respectively. In this embodiment, the quantum well active layer 3 is composed of six periods of quantum stacks 31 stacked in sequence. The quantum stack 31 includes a quantum barrier layer 311 and a quantum well layer 312. The quantum barrier layer 311 is 12nm Al _0.55 Ga _0.45 N quantum barrier, and the Si doping concentration of the quantum barrier layer 311 is 5×10 ¹⁸ -1×10 ¹⁹ ; the quantum well layer is a 3nm Al _0.45 Ga _0.55 N quantum well, and the quantum well layer is not doped. In addition, preferably, the thickness of the N-type AlGaN contact layer is 2-3 μm, and the Si doping concentration is 5×10 ¹⁸ to 1×10 ¹⁹ ; the thickness of the P-type AlGaN carrier transport layer is 25 nm, and the Mg-doped The concentration is 1×10 ¹⁹ to 3×10 ¹⁹ ; the thickness of the P-type GaN contact layer is 300 nm, and the Mg doping concentration is 1×10 ¹⁹ to 5×10 ¹⁹ .

Please refer to FIG. 3 . FIG. 3 is a schematic diagram of the principle of an embodiment of the quantum barrier-doped deep ultraviolet LED in the present invention. The principle of the quantum barrier-doped deep ultraviolet LED is described in detail in conjunction with FIG. 3 . In Figure 3, a is the case where the quantum barrier layer is not doped. Due to the piezoelectric polarization generated by the lattice mismatch and the spontaneous polarization of the AlGaN material itself, a very strong polarization electric field is generated at the interface, and the quantum well The energy band bending of the quantum well leads to the separation of the wave functions of the electrons and hole carriers in the quantum well, which reduces the probability of their radiative recombination, which eventually leads to a low internal quantum efficiency in the case of no doping; Fig. b in 3 is the case where the quantum barrier layer is doped with an appropriate amount of Si. When the quantum barrier layer is doped with an appropriate amount of silicon impurities, the reverse electric field generated by the activation of the silicon impurities can effectively shield the polarization electric field of the quantum barrier itself, thereby reducing the quantum barrier. The inclination of the energy band in the active region of the well increases the wave function overlap rate of carriers inside the quantum well, thereby increasing the probability of radiative recombination and realizing the improvement of the quantum efficiency in the deep ultraviolet LED.

The second solution provided by the present invention is specifically a method for preparing a quantum barrier-doped deep-ultraviolet LED. This method mainly uses metal-organic chemical vapor deposition to sequentially deposit an N-type AlGaN contact layer on a sapphire substrate. Well active layer, P-type AlGaN carrier transport layer and P-type GaN contact layer. In this embodiment, when preparing quantum barrier-doped deep ultraviolet LEDs, the Ga source used is trimethylgalliumTMGa, the Al source is trimethylgalliumTMAl, the nitrogen source is ammonia _NH3 , and the carrier gas is hydrogen The dopant sources of H ₂ , N-type and P-type are silane SiH ₄ and dimagnesium Cp ₂ Mg respectively; the preferred temperature conditions for depositing each layer structure are as follows: the reaction temperature for depositing N-type AlGaN contact layer is 1050-1080 °C, the reaction temperature for depositing the quantum well active layer is 1050-1080 °C, the reaction temperature for depositing the P-type AlGaN carrier transport layer is 1050-1080 °C, and the reaction temperature for depositing the P-type GaN contact layer is 950 °C ~1000°C.

Since the quantum barrier-doped deep ultraviolet LED preparation method in the second solution is used to prepare the quantum barrier-doped deep ultraviolet LED in the aforementioned first solution, the structure of the quantum barrier-doped deep ultraviolet LED in the two solutions and functions should be consistent.

Further, in order to study the relationship between the doping concentration of the quantum barrier layer and the coverage of the wave function, the carrier concentration of the quantum well layer, and the luminous power of the above-mentioned quantum barrier-doped deep ultraviolet LED, tests were carried out. For specific data, please refer to Fig. 4~6. Wherein, Fig. 4 is a graph of the relationship between the doping concentration of the quantum barrier layer and the wave function coverage and the light output power in an embodiment of the deep ultraviolet LED doped with quantum barriers in the present invention. It can be seen from Fig. 4 that with With the increase of the Si doping concentration of the quantum barrier layer, both the wave function overlap rate and the luminous power show a gradual upward trend, but the final luminous power will have a maximum value and cannot be continuously increased; Fig. 5 is the quantum barrier doped in the present invention. The curve relationship between the hole carrier concentration of the quantum well layer and the doping concentration of the quantum barrier layer in an embodiment of the deep ultraviolet LED can be seen from Fig. 5, as the Si doping concentration of the quantum barrier layer increases, the quantum well The concentration of hole carriers in the layer shows a downward trend, indicating that the gradual increase in Si doping concentration helps to gradually reduce the energy band gradient in the quantum well layer; Fig. 6 is a deep ultraviolet LED doped with quantum barriers in the present invention. The curve relationship between the luminous power and the doping concentration of the quantum barrier layer in the embodiment, as can be seen from Figure 6, with the increase of the Si doping concentration of the quantum barrier layer, the luminous power of the deep ultraviolet LED shows a trend of rising first and then falling , the initial luminous power gradually increases with the increase of Si doping concentration, when the optimal doping concentration is exceeded, the excessive decline of hole carriers gradually inhibits the luminous power of deep ultraviolet LEDs. Based on the data representations in Figures 4 to 6, it can be seen that if the luminous performance of the deep ultraviolet LED needs to be maintained at the best state, it is necessary to accurately control the Si doping concentration; and the optimal Si doping concentration of the quantum barrier layer in the present invention is 5×10 ¹⁸ ～1×10 ¹⁹ , and the deep ultraviolet LED prepared by this Si two-dimensional surface doping method has the best effect.

Different from the situation in the prior art, the present invention provides a deep ultraviolet LED doped with quantum barriers and a preparation method, which uses quantum barrier doping to realize the polarization self-shielding effect, and improves the carrier wave function overlap inside the quantum well. efficiency, thereby increasing the light output power of the deep ultraviolet LED.

The above-mentioned embodiments only express the implementation manner of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (8)

1. A quantum barrier doped deep ultraviolet LED, characterized in that, comprises a sapphire substrate, an N-type AlGaN contact layer, a quantum well active layer, a P-type AlGaN carrier transport layer and a P-type GaN contact layer, An N-type AlGaN contact layer, a quantum well active layer, a P-type AlGaN carrier transport layer and a P-type GaN contact layer are sequentially arranged on the sapphire substrate; The quantum well active layer is composed of 6 periods of quantum stacks stacked sequentially, the quantum stacks include a quantum barrier layer and a quantum well layer, and the quantum barrier layer is a 12nm Al _0.55 Ga _0.45 N quantum barrier, and The Si doping concentration of the quantum barrier layer is 5×10 ¹⁸ -1×10 ¹⁹ . 2 . The quantum barrier doped deep ultraviolet LED according to claim 1 , wherein the quantum well layer is a 3nm Al _0.45 Ga _0.55 N quantum well, and the quantum well layer is not doped. 3. The quantum barrier-doped deep ultraviolet LED according to claim 1, characterized in that, the thickness of the N-type AlGaN contact layer is 2-3 μm, and the Si doping concentration is 5×10 ¹⁸ to 1× 10 ¹⁹ . 4. The quantum barrier doped deep ultraviolet LED according to claim 1, characterized in that, the thickness of the P-type AlGaN carrier transport layer is 25 nm, and the Mg doping concentration is 1×10 ¹⁹ ~3 ×10 ¹⁹ . 5 . The quantum barrier doped deep ultraviolet LED according to claim 1 , wherein the thickness of the P-type GaN contact layer is 300 nm, and the Mg doping concentration is 1×10 ¹⁹ -5×10 ¹⁹ . 6. A quantum barrier doped deep-ultraviolet LED preparation method, characterized in that the specific steps are to sequentially deposit an N-type AlGaN contact layer, a quantum well active layer, and a P-type AlGaN contact layer on a sapphire substrate by metal-organic chemical vapor deposition. AlGaN carrier transport layer and P-type GaN contact layer; The quantum barrier doped deep ultraviolet LED preparation method is used for preparing the quantum barrier doped deep ultraviolet LED in any one of claims 1-5. 7. according to the quantum barrier-doped deep-ultraviolet LED preparation method described in claim 6, it is characterized in that, when preparing the quantum barrier-doped deep-ultraviolet LED, the Ga source that adopts is trimethyl gallium TMGa, The Al source is trimethylgallium TMAl, the nitrogen source is ammonia NH ₃ , the carrier gas is hydrogen H ₂ , and the N-type and P-type doping sources are silane SiH ₄ and dimagnesocene Cp ₂ Mg respectively. 8. The quantum barrier-doped deep ultraviolet LED preparation method according to claim 6, characterized in that the reaction temperature when depositing the N-type AlGaN contact layer is 1050-1080°C; The reaction temperature when depositing the quantum well active layer is 1050-1080°C; The reaction temperature when depositing the P-type AlGaN carrier transport layer is 1050-1080°C; The reaction temperature when depositing the P-type GaN contact layer is 950-1000°C.