METHOD FOR MANUFACTURING INDIUM GALLIUM NITRIDE QUANTUM WELL

Abstract

A method for manufacturing an indium gallium nitride quantum well is disclosed. The method includes providing a substrate in a process chamber, with the substrate including a gallium nitride layer. Having the process chamber reach a process vacuum. Providing a nitrogen molecular beam in plasma state, an indium molecular beam and an aluminum molecular beam into the process chamber simultaneously, controlling a flow rate ratio of the indium molecular beam to the aluminum molecular beam, and forming an indium aluminum nitride film on the gallium nitride layer, with the flow rate ratio being 0.6, 1.0, 1.29, 1.67 or 3.0. Forming an indium gallium nitride quantum well on the indium aluminum nitride film.

Claims

1. A method for manufacturing an indium gallium nitride quantum well, comprising: providing a substrate in a process chamber, wherein the substrate includes a gallium nitride layer; having the process chamber reach a process vacuum; providing a nitrogen molecular beam in plasma state, an indium molecular beam and an aluminum molecular beam into the process chamber simultaneously, controlling a flow rate ratio of the indium molecular beam to the aluminum molecular beam, and forming an indium aluminum nitride film on the gallium nitride layer, wherein the flow rate ratio is 0.6, 1.0, 1.29, 1.67 or 3.0; and forming an indium gallium nitride quantum well on the indium aluminum nitride film.

2. The method as claimed in claim 1, wherein the process vacuum is between 10.sup.-6 and 10.sup.-11 torr.

3. The method as claimed in claim 1, wherein during forming the indium aluminum nitride film, the process chamber is maintained at a growth temperature of 530° C. stably, at a growth vacuum between 10.sup.-5 and 10.sup.-6 torr, and for a duration of 120 minutes.

4. The method as claimed in claim 1, wherein a flow rate of the nitrogen molecular beam is between 10.sup.-5 and 10.sup.-6 torr, a flow rate of the indium molecular beam is between 1.5x10.sup.-8 and 3.0x10.sup.-8 torr, and a flow rate of the aluminum molecular beam is between 1.0x10.sup.-8 and 2.5x10.sup.-8 torr.

5. The method as claimed in claim 1, wherein a chemical formula of the indium gallium nitride quantum well is In.sub.xGa.sub.1-xN, a chemical formula of the indium aluminum nitride film is In.sub.yA1.sub.1-yN, and values of x and y are analyzed to represent indium contents in the indium gallium nitride quantum well and the indium aluminum nitride film, respectively.

6. The method as claimed in claim 5, wherein the value of x is adjusted between 13.0% to 18.7%, the value of y is adjusted between 28.9% to 33.5%, and the indium gallium nitride quantum well emits blue light.

7. The method as claimed in claim 5, wherein the value of x is adjusted between 19.9% to 27.7%, the value of y is adjusted between 34.6% to 40.9%, and the indium gallium nitride quantum well emits green light.

8. The method as claimed in claim 5, wherein the value of x is adjusted between 33.9% to 43.8%, the value of y is adjusted between 46.0% to 54.1%, and the indium gallium nitride quantum well emits red light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0018] A method for manufacturing an indium gallium nitride quantum well according to a preferred embodiment includes steps of providing a substrate in a vacuum chamber; providing an indium/aluminum molecular beam assisted by a nitrogen molecular beam; forming an indium aluminum nitride film on the substrate; and forming an indium gallium nitride quantum well on the indium aluminum nitride film.

[0019] The substrate includes a gallium nitride layer, which is formed on a sapphire substrate of aluminum oxide (Al.sub.2O.sub.3) through Metal-Organic Chemical Vapor Deposition (MOCVD). The gallium nitride layer may be a thin film with a thickness of 4.5 micrometers.

[0020] Before putting the substrate into a molecular beam epitaxy (MBE) system, clean the substrate first with solvents such as acetone, isopropanol, water, etc., and then clean the substrate with nitrogen. Sequentially convey the substrate into each chamber of the molecular beam epitaxy system for segments of vacuum process. For example, put the substrate into a load lock chamber for 4 hours at 180° C. in order to remove moisture. Then, send the substrate by a robotic arm to a buffer chamber and heat up to 550° C. in order to further remove impurities, and carry it to a process chamber of the molecular beam epitaxy system.

[0021] The process chamber is adapted to reach a process vacuum, so that the substrate is in an ultra-high vacuum state. A nitrogen molecular beam in plasma state, an indium molecular beam and an aluminum molecular beam are introduced into the process chamber simultaneously. It is preferable to control a flow rate ratio of the indium molecular beam to the aluminum molecular beam as 0.6, 1.0, 1.29, 1.67, or 3.0. The process chamber is maintained at a growth temperature of 530° C. stably, at a growth vacuum between 10.sup.-5 and 10.sup.-6 torr, and for a duration of 120 minutes in order to form the indium aluminum nitride film on the gallium nitride layer of the substrate. The process vacuum is between 10.sup.-6 and 10.sup.-11 torr, a flow rate of the nitrogen molecular beam is between 10.sup.-5 and 10.sup.-6 torr, a flow rate of the indium molecular beam is between 1.5x10.sup.-8 and 3.0x10.sup.-8 torr, and a flow rate of the aluminum molecular beam is between 1.0x10.sup.-8 and 2.5x10.sup.- .sup.8 torr.

[0022] It can be seen from the experimental results that when the thin film thickness of the indium aluminum nitride film is about 147 nm, cracks would occur in the thin film if the lattice constant mismatch is greater than 2.4%, and the thin film defects could be reduced if the lattice constant mismatch is less than 1.0%. Moreover, the lattice constant mismatch can be adjusted by controlling the flow rate ratio of the indium molecular beam to the aluminum molecular beam. The flow rate ratio of the indium molecular beam to the aluminum molecular beam are adjusted by temperature control. For example, after the metal molecular beams are heated to a predetermined temperature, a baffle is opened so that the molecular beams are emitted to the surface of the substrate in vapor state.

[0023] Further, an indium gallium nitride quantum well can be grown on the indium aluminum nitride film, so that the lattices of the indium gallium nitride quantum well and the lattices of the indium aluminum nitride film match with each other to reduce lattice defects. Among them, the chemical formula of the indium gallium nitride quantum well is In.sub.xGa.sub.1-xN, and the chemical formula of the indium aluminum nitride film is In.sub.yAl.sub.1-yN. By using Energy-Dispersive X-ray Spectroscopy (EDS) to analyze the composition ratio of the indium gallium nitride quantum well and the indium aluminum nitride film, the values of x and y (less than 1 and greater than 0) can be obtained. The values of x and y represent the indium contents of the indium gallium nitride and in the indium aluminum nitride, respectively. When x ranges from 13.0% to 18.7% and y ranges from 28.9% to 33.5%, the indium gallium nitride quantum well emits blue light; when x ranges from 19.9% to 27.7% and y ranges from 34.6% to 40.9%, the indium gallium nitride quantum well emits green light; and when x ranges from 33.9% to 43.8% and y ranges from 46.0% to 54.1%, the indium gallium nitride quantum well emits red light.

[0024] Based on the above, the method for manufacturing an indium gallium nitride quantum well according to the embodiment controls the growth temperature and molecular beam flow rate in the molecular beam epitaxy system, so that the defects are reduced in the formed indium aluminum nitride film, and the quantum well efficiency of the indium gallium nitride quantum well grown subsequently is improved. Furthermore, adjusting the indium contents of the indium aluminum nitride film and the indium gallium nitride quantum well allows the indium gallium nitride quantum well to emit light of different wavelengths, which can be applied to photoelectric components required for various working light wavelengths.

[0025] Although the invention has been described in detail with reference to its presently preferable embodiments, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the appended claims.