KR100881053B1 - Nitride-based light emitting device - Google Patents

Abstract

The present invention relates to the manufacture of a nitride-based light emitting device consisting of a buffer layer, an n-type nitride semiconductor layer, an active layer and a p-type nitride semiconductor layer, characterized in that the indium escape prevention layer is inserted into the active layer consisting of a quantum well layer and a quantum barrier layer. do. Through this, indium re-evaporation in the quantum well layer can be suppressed, and a nitride-based light emitting device having high brightness can be realized by improving the interface between the quantum well layer and the quantum barrier layer.

Description

Nitride-based light emitting device {NITRIDE BASED LIGHT EMITTING DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride-based light emitting device, wherein an indium escape prevention layer is inserted into an active layer consisting of a quantum well layer and a quantum barrier layer, thereby preventing the indium from being contained in the quantum well layer containing a large amount of indium. The present invention relates to the fabrication of a nitride-based light emitting device having high brightness through improved properties of the quantum well layer and the quantum barrier interface.

In general, nitride-based semiconductors are widely used in blue / green light emitting diodes or laser diodes as light sources for full-color displays, traffic lights, general lighting, and optical communication devices. The nitride-based light emitting device includes an InGaN-based multi-quantum well structured active layer disposed between n-type and p-type nitride semiconductor layers, and generates and emits light based on the principle of recombination of electrons and holes in the active layer.

In general, the optimal growth temperature of the quantum well layer is lower than the growth temperature of the quantum barrier layer due to the miscibility of InN in GaN. The GaN or InGaN layer at such low growth temperature reduces the decomposition rate of NH3, thereby forming a thin film lacking nitrogen atoms. In addition, since nitrogen atoms have a high equilibrium vapor pressure characteristic, indium droplets are generated in the InGaN layer grown at a low temperature.

For the above reason, in order to manufacture a high quality light emitting device, a quantum barrier layer must be grown at a higher temperature after growing a quantum well layer containing a large amount of indium. However, after the quantum well layer is grown, a large amount of indium is released from the quantum well layer while the temperature is increased to grow a high temperature quantum barrier layer, resulting in phase segregation and composition fluctuation. The light emitting device having a shorter wavelength than the planned wavelength can be obtained, and the light emitting device can be manufactured. In addition, as the interface between the quantum well layer and the quantum barrier layer is damaged, the leakage characteristic is increased, thereby causing a problem of lowering the internal quantum efficiency.

The present invention is to solve the problems of the prior art described above, indium contained in the quantum well layer by inserting the indium escape prevention layer in the quantum well layer and quantum barrier layer of the active layer, more preferably immediately after the growth of the quantum well layer The present invention relates to the fabrication of a nitride-based light emitting device having a high brightness characteristic by preventing the separation of the quantum well layer and the quantum barrier interface.

In order to solve the above technical problem, the nitride-based light emitting device of the present invention is composed of an n-type nitride semiconductor layer, an active layer and a p-type nitride semiconductor layer, the active layer is a quantum well layer, indium escape layer and quantum barrier layer, respectively At least one.

In this case, the indium escape prevention layer is preferably formed immediately after the quantum well layer.

The indium escape prevention layer may be 1/2 to 2 times the thickness of the quantum well layer.

In addition, the quantum well layer may be grown at 700 ~ 800 ℃, the quantum barrier layer may be grown at a temperature 50 ~ 200 ℃ higher than the quantum well layer, the indium escape layer is the same as the quantum well layer Can be grown at a temperature.

In addition, in one embodiment of the present invention, the indium escape prevention layer may not contain indium, and the indium content of the indium escape prevention layer may be the same as the indium content of the quantum barrier layer.

In another embodiment of the present invention, hydrogen may be added to the indium escape prevention layer.

In addition, in another embodiment of the present invention, the indium escape prevention layer may contain an n-type impurity, wherein the indium escape prevention layer adjacent to the n layer of the indium escape prevention layer has more n-type impurities than the indium escape prevention layer adjacent to the p layer. Preferably, the indium escape prevention layer may have an n-type impurity concentration in a range of 1 × 10 ¹⁷ / cm 3 to 5 × 10 ¹⁸ / cm 3.

As described above, according to the present invention, the indium escape prevention layer is a nitride-based light emitting device having a high brightness characteristics by preventing the separation of indium contained in the quantum well layer and at the same time improve the characteristics of the interface between the quantum well layer and the quantum barrier layer I can make it.

Hereinafter, with reference to the accompanying drawings will be described the present invention in more detail.

1 is a cross-sectional view of a nitride semiconductor device according to an embodiment of the present invention.

Referring to FIG. 1, in the nitride-based semiconductor device, an n-type nitride semiconductor layer 2-3 and an active layer 2-4 are sequentially formed after forming a buffer layer 2-2 on the substrate 2-1. ) And a p-type nitride semiconductor layer 2-5. The nitride semiconductor device according to the present invention includes the active layer 2-4 including the quantum well layer 2-b and the quantum barrier layer 2-c.

In a specific embodiment of the invention, the active layer comprises at least a quantum well layer of In _x Ga _{1- x} N (0.1 <x <1) and a quantum barrier layer of In _y Ga _{1- y} N (0 <y <0.5). It may be a multi-quantum well structure formed by repeating twice, of course, may be a single quantum well structure. The In content x of the quantum well layer has a larger value than the In content y of the quantum barrier layer. In this case, the indium escape prevention layer next to the quantum well layer has the same value as the In content y of the quantum barrier layer or does not contain indium.

A first embodiment of the nitride based light emitting device according to the present invention is as follows.

Growth methods of nitride-based light emitting devices include metal organic chemical vapor deposition (MOCVD), molecular beam growth (MBE; Molecular Beam Epitaxy) and hydride vapor phase growth (HVPE). Various methods can be used, and the present embodiment uses organometallic chemical vapor deposition (MOCVD).

Referring to FIG. 2, a buffer layer 2-2, an n-type nitride semiconductor layer 2-3, an active layer 2-4, and a p-type nitride semiconductor layer 2-5 are formed on a substrate 2-1. Form sequentially. In this case, the active layer is composed of a quantum well layer 2-b, an indium escape prevention layer 2-a, and a quantum barrier layer 2-c.

The substrate refers to a wafer for fabricating a nitride-based light emitting device, and uses a heterogeneous substrate such as sapphire (Al 2 O 3), silicon carbide (SiC), silicon (Si), gallium arsenide (GaAs), or the like. At least one of the substrates is used. In this embodiment, a crystal growth substrate made of sapphire is used.

The buffer layer 2-2 is to reduce lattice mismatch between the substrate and subsequent layers during crystal growth on the substrate, and may include InAlGaN series, SiC, or ZnO. In this embodiment, a buffer layer composed of InAlGaN series is used.

The n-type nitride semiconductor layer 2-3 is a layer in which electrons are generated, and an n-type nitride semiconductor layer doped with Si is used. In this embodiment, an impurity concentration of 1 × 10 ¹⁷ / cm 3 to 5 × 10 ¹⁹ / cm 3 is used as an n-type nitride semiconductor layer by using an inert gas such as SiH 4 or Si 2 H 4, or by using an MO source such as DTBSi. It is possible to form an n-type nitride semiconductor layer having a thickness of 1.0 ~ 5.0㎛.

Next, the active layer 2-4 was formed. The active layer (2-4) is In _x Ga1 _{1- x} N (0.1 <x <1) quantum well layer (2-a) and In _y Ga _{1 -y} N in nitrogen atmosphere to improve indium incorporation (0 <y <0.5) The quantum barrier layer 2-b formed a multi-quantum well structure consisting of two or more repetitions of 10 times or less. More preferably, the quantum well layer 2-b has a thickness of 1-4 nm and an In content (0.1 <x <0.4), and grows at a growth temperature of 700-800 degrees.

Next, hydrogen is added to make indium the same as that of the quantum barrier layer (2-c) while maintaining the growth temperature, or to evenly spread the indium in the quantum well layer (2-b) while the indium is interrupted. While the indium escape prevention layer (2-a) is grown to a thickness corresponding to twice the 1/2 of the quantum well layer (2-b).

Next, the growth temperature is raised to 50-200 ℃ higher than the quantum barrier layer with a constant heating rate (ting-rate), and then the quantum barrier layer (2-c) is 5-20 nm thick and indium content (0 < y <0.2). In addition, the active layer 2-4 including the indium escape preventing layer 2-a may be n-type impurity doped to reduce the operating voltage of the nitride-based light emitting device and to improve the quality of the film. The concentration may be 1 × 10 ¹⁷ / cm 3 to 5 × 10 ¹⁸ / cm 3.

Next, a p-type nitride semiconductor layer 2-5 doped with Mg is formed on the active layer 2-4. Here, trimethylgallium (TMGa) or triethylgallium (TEGa) may be used as a source gas for Ga, and ammonia (NH 3), dimethylhydrazine (DMHy) may be used as a source gas for N, and a source for Mg. As gas, CP ₂ Mg or DMZn may be used. By using this, a p-type nitride semiconductor layer 2-5 having a thickness of Mg 1 to 3 µm of 3 to 8 x 10 ¹⁷ / cm 3 is formed.

(Comparative Example)

A nitride light emitting device was manufactured under the same conditions as in the above embodiment, except for the indium escape preventing layer employed in the present invention.

2 shows the results of the measurement of PL (photo-luminesence) at room temperature of the nitride light emitting device obtained in Examples and Comparative Examples. As shown in FIG. 2, it was confirmed that the PL half-width of the example was sharper than the half-width of the comparative example and at the same time, the PL peak value was shifted toward the longer wavelength. This may be understood as a phenomenon in which phenomena such as indium separation and indium hybridization contained in the quantum well layer are suppressed by the indium escape prevention layer. Although not included in this electronic document, high resolution x-ray diffraction (HRXRD) measurements of the above examples and the comparative examples resulted in the 2nd-5th interface half width of the examples being sharper than the comparative example, and increasing the average indium content. It is thought that the anti-separation layer actually helps to improve the interface between the quantum well layer and the quantum barrier layer.

As such, by inserting the indium escape prevention layer according to the present invention between the active layer consisting of the quantum well layer and the quantum barrier layer, the separation of the indium contained in the quantum well layer is prevented and the improvement of the interface between the quantum well layer and the quantum barrier layer is improved. It can greatly improve the characteristics of high brightness.

In the above embodiment, a nitride-based light emitting device has been described as an example, but it is apparent to those skilled in the art that the present invention can be advantageously employed in other nitride-based optical devices having a similar structure, such as semiconductor laser devices.

As described above, the present invention has been described in detail through preferred embodiments, but the scope of the present invention is not limited to the specific embodiments and should be interpreted by the appended claims. In addition, those of ordinary skill in the art should understand that many modifications and variations are possible without departing from the scope of the present invention.

1 is a cross-sectional view of a nitride-based light emitting device according to the present invention.

FIG. 2 is a graph showing a PL (photo-luminesence) measurement result of the nitride-based light emitting device and the conventional nitride-based light emitting device according to the present invention.

<Code Description of Main Parts of Drawing>

2-1: substrate, 2-2: buffer layer

2-3: n-type nitride semiconductor layer

2-4: active layer

2-a: indium escape prevention layer, 2-b: quantum well layer, 2-c: quantum barrier layer

2-5: p-type nitride semiconductor layer

Claims (14)

In a nitride light emitting device comprising an n-type nitride semiconductor layer, an active layer and a p-type nitride semiconductor layer, The active layer is an In _x Ga _1-x N (0.1 <x <1) quantum well layer, an indium escape prevention layer located on the quantum well layer and containing In, and an In _y Ga _1- located on the indium escape prevention layer. A nitride-based light emitting device comprising _y N (0 <y <0.5, x> y) quantum barrier layer. delete The method of claim 1, The indium escape prevention layer is a nitride-based light emitting device, characterized in that 1/2 to 2 times the thickness of the quantum well layer. The method of claim 1, The quantum well layer is nitride-based light emitting device that is grown at 700 ~ 800 ℃. The method of claim 1, The quantum barrier layer is a nitride-based light emitting device that is grown at a temperature 50 ~ 200 ℃ higher than the quantum well layer. The method of claim 1, The indium escape prevention layer is a nitride-based light emitting device that is grown at the same temperature as the quantum well layer. delete The method of claim 1, The indium content of the indium escape prevention layer is a nitride-based light emitting device, characterized in that the same as the indium content of the quantum barrier layer. The method of claim 1, Nitride-based light emitting device, characterized in that hydrogen is added to the indium escape prevention layer. The method of claim 1, The indium escape prevention layer is a nitride-based light emitting device, characterized in that it contains n-type impurities. The method of claim 1, A nitride-based light emitting device according to claim 1, wherein the indium escape prevention layer adjacent to the n layer of the indium escape prevention layer contains more n-type impurities than the indium escape prevention layer adjacent to the p layer. The method according to claim 10 or 11, wherein The indium escape prevention layer is a nitride-based light emitting device, characterized in that the n-type impurity concentration has a range of 1 × 10 ¹⁷ / cm 3 ~ 5 × 10 ¹⁸ / cm 3. In the nitride-based light emitting device manufacturing method consisting of an n-type nitride semiconductor layer, an active layer and a p-type nitride semiconductor layer, In _x Ga _1-x N (0.1 <x <1) quantum well layer is grown at a temperature of 700 ~ 800 ℃, Growing an indium escape preventing layer containing In on the quantum well layer at the same temperature as the quantum well layer is grown; A gallium nitride-based light emitting device comprising growing an In _y Ga _1-y N (0 <y <0.5) quantum barrier layer on the indium escape prevention layer at a temperature 50 to 200 degrees higher than the temperature at which the quantum well layer is grown Manufacturing method. The method according to claim 13, The indium escape prevention layer and the quantum barrier layer is a gallium nitride-based light emitting device manufacturing method is grown by supplying In at the same flow rate.

Images