KR100223836B1 - Gallium nitride light emitting diode and manufacturing method of the same - Google Patents

Abstract

A gallium nitride light emitting diode and a method of manufacturing the same are provided for removing crystal defects caused by lattice mismatch and difference in temperature expansion coefficient between a substrate and a light emitting element formed on the substrate.

In order to achieve the object of the present invention, a method of manufacturing a gallium nitride light emitting diode includes the steps of preparing an n ⁺ gallium nitride substrate obtained by doping with salicon after growing by homogeneous thin film growth using a halogen vapor thin film growth method; N-type cladding layer, active layer and n-type (GaxAl _1-x N, InxGa _1-x N and P-type GaxAl _1-x N, respectively) were grown on the n ⁺ type gallium nitride substrate sequentially by an organometallic thin film growth method. Forming a P-type cladding layer and forming P-type and n-type electrodes on the P-type cladding layer and the substrate, respectively.

Description

Gallium Nitride Light Emitting Diode and Manufacturing Method Thereof

The present invention is a gallium nitride light emitting diode for producing a high brightness and high magnification light emitting device by growing a gallium nitride-based thin film by organometallic chemical vapor deposition (M0CM) on a gallium nitride substrate made by a halogen vapor deposition (HVPE) method and its It relates to a manufacturing method.

As a technique of personalizing the conventional light emitting device, the special blue light emitting diodes, and the efficiency, examples of the disclosed invention are disclosed in Japanese Patent Laid-Open No. 4-321280.

In the conventional invention, as shown in FIG. 1, the GaxA1 _1-x N (0x≤1) buffer layer 2, which is a gallium nitride compound semiconductor, and GaxAl _1-x N coated on the sapphire substrate ₁ (0x ≦ 1) N-type cladding layer 3, a light emitting active layer 4 coated with Zn and Si, and a P-type cladding 5 of GaxAl _1-x N (α ≦ ₁ ) coated with Mg It is laminated | stacked sequentially and the P-type electrode 6 and the n-type electrode 7 are formed.

In the conventional invention, a blue light emitting diode is manufactured by using a pn junction structure and a meta1-intulator-semiconductor (MIS) structure, but there is a lattice mismatch (13.8%) and a thermal window coefficient difference between a gallium nitride (GaN) and a sapphire substrate. Because of (25%), even when using a buffer layer of Ga _x Al _1-x N (0x≤1), crystal defects in the thin film growth layer are present in 10 ⁸ -10 ¹⁰ cm ^-2 and such hetero epitaxy ) Is limited by the above-described lattice mismatch and thermal expansion coefficient difference in improving the quality of the thin film grown on the sapphire substrate, even if the growth conditions of the buffer layer are optimized.

In addition, even when using SiC substrate with much less than sapphire substrate with 3.4% gallium nitride (GaN) and lattice mismatch, the crystal defect of the grown thin film layer is about 10 ⁸ cm ^-2 like that of sapphire substrate. Did not improve much.

Accordingly, the present invention has been invented in view of the above-described problems of the prior art, and a gallium nitride light emitting diode for removing crystal defects caused by a lattice mismatch and difference in temperature hoe coefficient between a substrate and a light emitting element formed on the substrate and its It is to provide a manufacturing method.

1 is a schematic cross-sectional view of a conventional gallium nitride light emitting diode.

2 is a schematic cross-sectional view of a gallium nitride light emitting diode of the present invention.

* Explanation of symbols for main parts of the drawings

1: sapphire substrate 2: buffer layer

3, 11: n-type cladding layer 4, 12: active layer

5, 13: P-type cladding layer 6, 7, 14, 15: electrode

In order to achieve the object of the present invention, a method of manufacturing a gallium nitride light emitting diode includes the steps of preparing an n ⁺ gallium nitride substrate obtained by doping silicon after growing by homogeneous thin film growth using a halogen vapor thin film growth method; An n-type clad layer by growing n-type (GaxAl _1-x N, In _x Ga _1-x N and P-type GaxAl _1-x N, respectively) by the organic metal thin film growth method sequentially on the n ⁺ type gallium nitride substrate; Forming an active layer and a P-type cladding layer, and forming P-type and n-type electrodes on the P-type cladding layer and the substrate, respectively.

In addition, the gallium nitride light emitting diode of the present invention uses a halogen vapor phase thin film growth method.

After grown to homogeneous thin film growth of silicon doped by the resulting n ⁺ type gallium nitride substrate, the n ⁺ type silicon doped gallium nitride substrate in the Ga _x Al _1-x N of n-type formed by growing a (0x≤1) cladding A layer, an active layer formed by growing In _x Ga _1-x N (0x ≦ ₁ ) on the n-type cladding layer, and grown on a magnesium doped Ga _x Al _1-x N (0x ≦ ₁ ) layer And p-type cladding layers formed on the substrate, and n-type and P-type electrodes formed on the substrate lower portion and the P-type cladding layer, respectively.

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

Figure 2 is a schematic cross-sectional view of a gallium nitride light emitting diode of the present invention, n ⁺ of the 5 ~ 10 × 10 ¹⁸ cm ³ impurity concentration obtained by silicon doping after growing by homogenous thin film growth (Homo epitaxy) using a halogen vapor phase film growth method An n-type clad layer 11 formed by growing a silicon-doped Ga _x Al _1-x N (0x≤1) to a thickness of 3-5 μm on the GaN substrate 10 and the n ⁺ GaN substrate 10. ), An active layer 12 formed by growing In _x Ga _1-x N (0x≤1) on the n-type cladding layer 10 at a thickness of 300-500 μs, and 5000 μs on the active layer 12. P-type cladding layer 13 formed by growing magnesium-doped Ga _x Al _1-X N (0x≤1) to a thickness, on the back surface of the substrate 10 and the front surface of the P-type cladding layer 13 Each of the N-type electrodes 14 and P-type electrodes 15 formed by evaporation is formed.

Each composition of the active layer is about x = 0.22 to 0.25 in the case of a blue light emitting device, and about x = 0.43 to 0.5 in the case of a pure green light emitting device.

The InxGa _1-x N active layer 12 forms a barrier layer of In _0.05 Ga _0.95 N on a well layer of In _{0.43 to 0.5} Al _{0.57 to 0.5} N (or In _{0.22 to 0.25} Al _{0.78 to 0.75} N), and this is several times. When the quantum well structure is formed alternately (3-5 times), the luminous efficiency can be further increased.

An embodiment of a method of manufacturing a gallium nitride light emitting diode having such a structure will be described.

First, gallium nitride (GaN) substrates doped with silicon are prepared to grow to a thickness of 300-350 μm by homogeneous thin film growth using a halogen vapor phase thin film growth method and to have an impurity concentration of 5 to 10 × 10 ¹⁸ cm ³ .

At this time, the silicon source uses SiH ₄ or Si ₂ H ₆ .

Next, an organic metal chemical vapor deposition method (MOCVD) was used to grow a Ga _x Al _1-X N (0x≤1) layer doped with silicon having a thickness of 3-5 μm at a temperature of 950-1050 ° C. in an NH ₃ atmosphere to form an N-type. A clad layer is formed.

Again, an active layer is formed on the N-type cladding layer by growing In _xG a _1-x N (0x ≦ ₁ ) having a thickness of 300-500 로 at a temperature of 720 ° to 850 °.

At this time, the composition ratio of In and Ga is adjusted according to the wavelength of the light emitting device.

For example, the blue light emitting device is about x = 0.22 to 0.25 and the pure green light emitting device is about x = 0.43 to 0.5.

In order to increase the luminous efficiency, the active layer of In _x Ga _1-x N is formed with a barrier layer of In _0.05 Al _0.95 N on a well layer of In _{0.22 to 0.25} Al _{0.78 to 0.75} N (or In _{0.43 to 0.5} Al _{0.57 to 0.5} N). It is formed into a quantum well structure formed by alternating several times.

After the formation of the active layer, the temperature was further raised to 1000 to 1050 ° C. to form a P-type cladding layer doped with Mg at a thickness of 5000 kPa.

Subsequently, the backside of the n ⁺ type GaN substrate was polished and wrapped with boron carbide or diamond powder to a thickness of 100 to 150 μm, polished with A1 ₂ O ₃ powder, the wafer was washed, and then n type metal Ti / Al. / Ni / Au was deposited in a conventional manner and annealed at 700 ° C. for 30 seconds to form an n-type ohmic contact electrode, and then deposited P-type metal Cr / Ni / Au on the P-type clad layer and at room temperature 500 ° C. for 30 seconds. Annealing to form a P-type ohmic contact electrode.

Thus, according to such a GaN light emitting diode and a method of manufacture of the present invention, the thin film grown on said n ⁺ type GaN substrate because it uses a n ⁺ -type GaN substrate obtained by growing a homogeneous thin film growth using a halogen vapor phase thin film growth (epitaxy Crystal defects can be reduced to 10 ⁵ cm ^-3 or less, which enables the growth of high quality thin films, which makes light emitting diodes with high brightness and high output (high efficiency), and makes n-type substrates on the back of the substrate. (Normally made on the same side) Etching process is eliminated, manufacturing process is simplified and only one P-type or n-type electrode needs to be bonded, so packaging is simple and yield is increased by easy cleaving process. By depositing a metal electrode on the back side, the electrode itself can be used as a reflection mirror, so that the luminous efficiency is increased.

Claims (7)

Preparing n ⁺ gallium nitride substrates obtained by doping silicon after growing by homogeneous thin film growth using halogen vapor phase thin film growth, and n-type GaxAl by organometallic thin film growth method on the n ⁺ gallium nitride substrate sequentially Growing _1-x N, In _xG a _1-x N and P-type GaxAl _1-x N to form an N-type cladding layer, an active layer, and a P-type cladding layer, respectively, on the P-type cladding layer and the substrate A method of manufacturing a gallium nitride light emitting diode, each step comprising forming a P-type n-type electrode. The method of claim 1, wherein _{x in} the active layer In _x Ga _1-x N is 0.22 to 0.25. The method of claim 1, wherein _{x in} the active layer In _x Ga _1-x N is 0.45 to 0.5. N ⁺ gallium nitride substrate obtained by silicon doping after growth by homogeneous thin film growth using halogen vapor deposition method, and Ga _x Al _1-X N (0x≤1) of silicon doping on the n ⁺ gallium nitride substrate An n-type cladding layer formed by growing, an active layer formed by growing In _x Ga _1-x N (0x≤1) on the n-type cladding layer, and Ga _x Al _1-x of magnetism doping on the active layer A gallium nitride light emitting diode having a P-type cladding layer formed by growing N (0x≤1), and n-type and P-type electrodes formed on the lower side of the substrate and on the P-type cladding layer, respectively. The gallium nitride light emitting diode of claim 4, wherein x of the active insect InxGa _1-X N is 0.22 to 0.25. The gallium nitride light emitting diode of claim 4, wherein _{x of} the active layer InGa _1-x N is 0.43 to 0.5. The gallium nitride light emitting diode of claim 4, further comprising a barrier layer of In _0.05 Ga _0.95 N formed on the active layer InxGa _1-x N (0x ≦ ₁ ).