KR20020095769A - GaN-BASED QUANTUM WELL LIGHT EMITTING DEVICES ENHANCED BY PLASMA TREATMENT AND DEVICE MANUFACTURING METHOD THEREOF - Google Patents

Abstract

PURPOSE: A method for fabricating a gallium nitride light emitting device of a quantum well structure by using a plasma treatment is provided to remarkably improve a light emitting characteristic of a light emitting diode(LED), by performing a plasma treatment on a gallium nitride thin film grown by a metal organic chemical vapor deposition(MOCVD) process. CONSTITUTION: A gallium nitride buffer layer of a uniform thickness is grown on a sapphire substrate at a uniform temperature. An n-type gallium nitride thin film having a single or multilayered quantum well structure is formed on the gallium nitride buffer layer by a MOCVD process. A gallium nitride cap layer is grown on the n-type gallium nitride thin film at a uniform temperature and a plasma treatment process is performed. A p-type gallium nitride layer of a uniform thickness is grown on the gallium nitride cap layer at a uniform temperature to finish the growth of the structure of the LED. A metal electrode is formed to fabricate the light emitting device.

Description

Quantum well structure gallium nitride-based light emitting device by plasma treatment and manufacturing method thereof {GaN-BASED QUANTUM WELL LIGHT EMITTING DEVICES ENHANCED BY PLASMA TREATMENT AND DEVICE MANUFACTURING METHOD THEREOF}

The present invention relates to a gallium nitride-based light emitting device and a manufacturing method thereof.

In recent years, gallium nitride-based light emitting devices have been widely applied to the blue and ultraviolet spectral regions, and are attracting attention as environmentally friendly semiconductor devices capable of maximizing energy savings. One of the most important problems to be solved in this application is to increase the luminescence properties.

To this end, a method of growing an active layer into a quantum well structure by organometallic chemical vapor deposition has been used. Methods of increasing the luminous efficiency by controlling the number of layers, thickness and indium (In) content of the quantum well structure or optimizing the electrode structure shape and packaging method for manufacturing a light emitting diode (LED) are mainly studied.

However, these methods are accompanied with difficulties due to the physical limitations of the light emitting diode (LED) structure and various interfacial phenomena occurring at the interface, and furthermore, it is difficult to establish and optimize the light emitting device manufacturing process.

An object of the present invention is to improve the luminous efficiency of LED by treating the gallium nitride-based thin film having a quantum well structure prepared by a general organic metal chemical vapor deposition method with a plasma. More specifically, the single or multilayer quantum well structure gallium nitride surface prepared by organometallic chemical vapor deposition is Cl ₂ / N ₂ , Cl ₂ / He, Cl ₂ / Ar, N ₂ / Ar, H ₂ / Ar and Ar, etc. Treatment by using plasma to improve the luminous efficiency of the active layer.

Further, by using the present invention to produce a gallium nitride-based light emitting diode (LED) it is characterized in that to improve the light emission characteristics. The present invention is equally applicable to single quantum well structure (SQW) and multi quantum well structure (MQWs).

1 is a view showing a growth structure of a single-layer or multi-layer quantum well structure gallium nitride light emitting diode according to the present invention.

2 is a schematic diagram of an inductively coupled high density plasma apparatus used for plasma treating a surface of a gallium nitride cap layer grown at low temperature on a light emitting active layer according to the present invention;

Figure 3 is a measurement result of the emission characteristics (PL) before and after plasma treatment of a single quantum well structure (GaN / SQW / n GaN / GaN / Sapphire) grown by organometallic chemical vapor deposition (MOCVD) method according to the present invention.

4 is a measurement result of light emission characteristics (PL) before and after plasma treatment of a multilayer quantum well structure (GaN / SQW / n GaN / GaN / Sapphire) grown by an organometallic chemical vapor deposition method according to the present invention.

5 is a manufacturing process diagram of the light emitting diode using the process procedure of the present invention.

Explanation of the code | symbol about main part of drawing

1: RF generator (13.56 MHz, ICP souece)

2: Matching box

3 Baratron gauge

4: purge gas

5: etching gas

6: RF generator (13.56 MHz, lower electrode)

7: turbo pump

8: Rotary and Booster Pump

Through the following preferred embodiment will be able to better understand the object and configuration of the invention.

In addition, with reference to the accompanying drawings will be described in detail a preferred embodiment of improving the optical emission characteristics by surface treatment of a single or multi-layer quantum well structure gallium nitride grown by the organic metal chemical vapor deposition according to the present invention using a high density plasma Let's do it.

1 illustrates a light emitting diode wafer structure having an indium gallium nitride / gallium nitride (InGaN / GaN) multilayer quantum well structure according to the present invention. After growing a gallium nitride buffer layer at a low temperature (560 ° C.) to a thickness of about 25 nm on a sapphire substrate, an N type gallium nitride (Si doped) base layer having a thickness of 2 to 4 μm thereon was formed at 1130 ° C. After growth, an active layer having a quantum well structure thereon is grown at 750 ° C., and a gallium nitride cap layer is grown at 1100 ° C. at about 100 nm, and then Cl ₂ / N ₂ , Cl ₂ / He, Cl ₂ / Ar, Cl ₂ / Xe, N ₂ / Ar, N ₂ / He, Cl ₂ / Xe, H ₂ / Ar, Cl ₂ / N ₂ / Ar, Cl ₂ / H ₂ / Ar, Cl ₂ / N ₂ / He, Ar, He, Xe and the like treatment, and P-type gallium nitride (Mg doping) having a thickness of about 100 nm on it is grown at high temperature (1050 ℃) to grow the quantum well LED structure Complete Trimethylgallium (TMGa), trimethylindium (TMIn), and ammonia (NH ₃ ) are used as precursors for the growth of gallium nitride-based thin films, and biscyclopenta-dienymagnesium (biscyclopenta-dienylmagnesium) is used as a dopant material. , Cp ₂ Mg), diethylzinc (DEZn) and silane (SiH ₄ ) are used.

2 is a schematic diagram of an inductively coupled high density plasma (ICP) device used to plasma treat a surface of a gallium nitride cap layer grown at low temperature on a light emitting active layer.

In the ICP device, supplying RF power (ie, ICP supply power) to the induction coil generates a magnetic field in the reactor, and thus, electrons are trapped in the reactor by the induced electric field, thereby generating a high density plasma even at low pressure. Electrons are to a collision frequency of the electrons and molecules increases as movement along a circular path in the reactor high density - to form a plasma ^{(10 11 10 12 cm -3)} . The ion density of the bulk plasma changes the voltage of the ICP RF generator so that the ion energy incident on the substrate surface is independently controlled by the devias generated when the power of the RF generator connected to the lower electrode changes.

3 is an example of measuring the light emission characteristics PL before and after plasma treatment of a single layer quantum well structure (GaN / SQW / n-GaN / GaN / Sapphire) grown by an organometallic chemical vapor deposition method. PL was measured after treating the thin film with Cl ₂ / Ar plasma while changing the RF power of the lower electrode to 200 W and 250 W at 800 W ICP source power, 40 mTorr.

When the plasma treatment was performed while changing the RF power of the lower electrode to 200 W and 250 W, the PL intensity at 2.7 eV corresponding to the blue wavelength was increased by 45% and 200%, respectively. This may be said to be due to the heat treatment effect by the plasma energy, the surface defect removal effect by the plasma ions and reactive species to improve the light emission characteristics.

4 is an example of measuring the light emission characteristics PL before and after plasma treatment of a multi-layer quantum well structure (GaN / 6MQWs / n-GaN / GaN / Sapphire) grown by organometallic chemical vapor deposition.

The PL was measured after treating the thin film with Cl ₂ / Ar plasma while changing the RF power of the ICP to 700 W and 800 W at an RF power of 200 W and a reactor pressure of 40 mTorr. The PL strength at 2.7 eV was 65% and 50% improvement.

5 is a process chart of manufacturing a gallium nitride-based light emitting device using the present invention. The first process of growing gallium nitride thin film of single (SQW) or multi-layer quantum well structure (MQWs) by organometallic chemical vapor deposition, the second process of plasma treatment of cap layer, and the growth of P-type gallium nitride after the second process The third step of completing the structure growth and the fourth step of forming the light emitting device by forming an etching and a metal electrode after the third step.

As described above, according to the present invention, the light emitting characteristics of the light emitting diode can be greatly improved by treating the gallium nitride-based thin film grown by the organic metal chemical vapor deposition method with plasma. The method used in the present invention is simple and easy to apply to the process, and is effective in realizing a high brightness optoelectronic device by improving light emission characteristics.

Claims (10)

In the manufacturing method of gallium nitride-based light emitting diode, Growing a gallium nitride buffer layer at a constant thickness and temperature on a sapphire substrate and growing an N-type gallium nitride thin film having a single or multilayer quantum well structure by organometallic chemical vapor deposition; A second step of growing a gallium nitride cap layer on the N-type gallium nitride thin film at a constant temperature and then treating the same with a plasma; A third step of growing a P-type gallium nitride at a constant thickness and temperature on the gallium nitride cap layer to complete the structure growth of the light emitting diode; And And a fourth step of forming an etched and metal electrode after the third step to manufacture the light emitting device. 4. A method of manufacturing a gallium nitride-based light emitting diode having a single layer or multilayer quantum well structure. The single layer or multi-layer quantum well structure according to claim 1, wherein the gallium nitride buffer layer is grown at 560 DEG C with a thickness of 25 nm, the N-type gallium nitride thin film is grown thereon, and the active layer is formed thereon. Method of manufacturing a gallium nitride-based light emitting diode having a. The method of claim 2, wherein the base layer of the N-type gallium nitride thin film is grown at 1130 ° C. with a thickness of 2 to 4 μm. The method according to claim 2, wherein the active layer of the N-type gallium nitride thin film is grown at 750 ° C. The method of claim 1, wherein the gallium nitride cap layer is grown at 1100 ° C. with a thickness of 100 nm. The method of claim 1, wherein the plasma is Cl ₂ / N ₂ , Cl ₂ / He, Cl ₂ / Ar, Cl ₂ / Xe, N ₂ / Ar, N ₂ / He having an ion density of 10 ^{8-10 14} cm ^-3 Or a monolayer comprising Cl ₂ / Xe, H ₂ / Ar, Cl ₂ / N ₂ / Ar, Cl ₂ / H ₂ / Ar, Cl ₂ / N ₂ / He, Ar, He, Xe, or the like. Method of manufacturing a light emitting diode having a multilayer quantum well structure. The method of claim 1, wherein, when a plasma treatment in a single-layer quantum well structures grown by metal organic chemical vapor deposition (CVD) 300 - 1500 W ICP source power; 1, varying from 760 mTorr RF power to the lower electrode from 50W to 500W Cl ₂ A method of manufacturing a light emitting diode having a single layer quantum well structure, wherein the thin film is treated with a / Ar plasma. The thin film of claim 1, wherein the plasma is treated in a multi-layer quantum well structure grown by MOCVD, while the ICP supply power is changed to 300-1500 W at an RF power of 10-600 W and a reactor pressure of 1-760 mTorr. A method of manufacturing a light emitting diode having a multilayer quantum well structure, characterized in that the treatment with Cl ₂ / Ar plasma. The method of claim 1, wherein the P-type gallium nitride is grown at 1050 ° C. with a thickness of 100 nm. In a gallium nitride-based light emitting diode, A gallium nitride buffer layer grown on the sapphire substrate; An N-type gallium nitride base layer thereon; A thin film having a single or multilayer quantum well structure thereon; A gallium nitride cap layer thereon; P-type gallium nitride thereon; A gallium nitride-based light emitting diode having a single layer or multilayer quantum well structure, characterized in that the etching and the metal electrode is formed.