TWI414087B - Method for growing a nonpolar gan layer on a sapphire substrate and a led structure thereof - Google Patents

Abstract

A method, for growing a nonpolar GaN layer on a sapphire substrate, includes: providing a predetermined surface on a sapphire substrate; directly growing a nonpolar GaN layer on the predetermined surface with a predetermined Ga/N value, wherein the nonpolar GaN layer is formed as a light-emitting layer to form a nonpolar GaN layer LED structure.

Description

Method for growing non-polar plane gallium nitride thin film on sapphire substrate and light-emitting diode structure thereof

The invention relates to a method for growing a non-polar plane gallium nitride thin film on a sapphire substrate and a light emitting diode structure thereof; in particular, a method for plasma assisted molecular beam epitaxy in m-plane sapphire A method of growing a non-polar surface [m-plane] gallium nitride thin film on a substrate and a light-emitting diode structure thereof.

In the manufacture of light-emitting components, the three-five semiconductor materials occupy a pivotal position. In particular, in the manufacture of light-emitting diode elements, light-emitting diodes using gallium nitride [GaN] and indium gallium nitride [InGaN] as light-emitting layers have attracted the most attention. However, since the growth direction of the light-emitting diode of most indium gallium nitride material systems is c-plane [c-plane], it causes the piezoelectric element to be internally affected by the built-in electric field, and the component is lowered. Overall luminous efficiency. Especially in the case of high current, it will reduce its external quantum effect (EQE), which is called the droop effect.

In general, in order to improve the droop effect, the light-emitting diode of the non-polar surface semiconductor material layer is currently passed through to overcome this droop effect. In fact, it is very important to choose a substrate for growth on a non-polar surface emitting diode. The light-emitting diode substrate currently mainly used includes a gallium nitride substrate, an m-plane zinc oxide [m-plane ZnO] substrate, a tantalum carbide (SiC) substrate, and an aluminum silicate [LiAlO ₂ ] substrate.

For example, the Republic of China Patent No. 468285 uses the molecular beam epitaxy system to grow without the need of thermal annealing activation treatment, that is, a gallium nitride-based light-emitting diode of the invention having a high hole concentration, which discloses the use of organic A GaN light-emitting diode manufactured by a metal chemical vapor deposition method and a molecular beam epitaxy system.

At present, it is most suitable for growing non-polar surface light-emitting diodes on a gallium nitride substrate, and good growth results are obtained. However, gallium nitride substrates are often difficult to obtain, and their manufacturing costs are expensive, and they are limited by the substrate area size. It is one square centimeter. In addition, the aluminum silicate substrate and the zinc oxide substrate are inferior in thermal stability. As for the tantalum carbide substrate, it has the disadvantage of being expensive to manufacture. Furthermore, the common disadvantages of growing non-polar surface nitrides are high frequency packing density and high stacking fault density.

In short, the above-mentioned light-emitting diode substrates each have the disadvantages of being expensive to manufacture, limited in substrate area size, and poor in thermal stability. Therefore, there is a need in the conventional light-emitting diode substrate to further select other substrate materials to improve the aforementioned technical disadvantages.

In view of the above, in order to improve the above disadvantages or meet the above requirements, the present invention provides a method for growing a non-polar plane gallium nitride thin film on a sapphire substrate and a light-emitting diode structure thereof, which are in the form of plasma assisted molecular beam epitaxy. A gallium nitride film is directly grown on the sapphire substrate to form a light-emitting layer for the purpose of fabricating a non-polar surface light-emitting diode.

The main object of the present invention is to provide a method for growing a non-polar plane gallium nitride thin film on a sapphire substrate and a light emitting diode structure thereof, and directly growing a gallium nitride film on a sapphire substrate by plasma assisted molecular beam epitaxy. In order to form a light-emitting layer for the purpose of fabricating a non-polar surface light-emitting diode.

In order to achieve the above object, a method for growing a non-polar plane gallium nitride film on a sapphire substrate comprises: providing a predetermined crystal plane on a sapphire substrate; and a predetermined ratio of nitrogen to gallium on a predetermined crystal plane of the sapphire substrate Directly forming a non-polar plane gallium nitride film; wherein the non-polar plane gallium nitride film forms a light-emitting layer.

The light emitting diode structure of the non-polar surface gallium nitride film grown on the sapphire substrate of the present invention comprises: a sapphire substrate comprising a predetermined crystal plane; and a non-polar plane gallium nitride film having a predetermined GaN The ratio is directly formed on a predetermined crystal plane of the sapphire substrate; wherein the non-polar plane gallium nitride film forms a light-emitting layer.

In the preferred embodiment of the invention, the predetermined crystal plane is an m-plane sapphire substrate.

In the preferred embodiment of the present invention, the non-polar plane gallium nitride film is formed by plasma assisted molecular beam epitaxy.

The predetermined nitrogen to gallium ratio of the preferred embodiment of the invention is 90, 80 or 70.

In order to fully understand the present invention, the preferred embodiments of the present invention are described in detail below and are not intended to limit the invention.

The method for growing a non-polar surface gallium nitride thin film on a sapphire substrate and the light emitting diode structure thereof can be applied to the manufacture of a nano light emitting diode and related technical field, but it is not intended to limit the present invention. The scope of application of the invention. For example, in the Republic of China Patent Application Publication No. 200947739, the tri-n-nitrogen semiconductor nanostructure and its luminescent diode invention patent case disclose a tri-n-nitrogen semiconductor nano-light emitting diode. Incorporate references.

A preferred embodiment of the present invention is a method for growing a non-polar plane gallium nitride film on a sapphire substrate, comprising the steps of: first, providing a predetermined crystal plane on a sapphire substrate, and the predetermined crystal plane is an m-plane [m plane a sapphire substrate; and then, a non-polar plane gallium nitride film is directly formed on the predetermined crystal plane of the sapphire substrate by a predetermined ratio of nitrogen to gallium, and the non-polar plane gallium nitride film is formed by plasma assisted molecular beam epitaxy And the non-polar plane gallium nitride film forms a light-emitting layer.

In a preferred embodiment of the present invention, plasma-assisted molecular beam epitaxy is used to directly grow m-plane gallium nitride on the m-plane sapphire substrate, and the gallium nitride film can be changed by adjusting the growth temperature and the ratio of the nitrogen plasma to the gallium. The crystal orientation, while allowing the growth of the m-plane GaN, is narrower. For example, the predetermined nitrogen to gallium ratio of the preferred embodiment of the invention is 90, 80, 70 or other ratio.

Briefly, the LED structure of the preferred embodiment of the present invention comprises the sapphire substrate and the non-polar plane gallium nitride film, and the non-polar plane gallium nitride film emits light.

In a preferred embodiment of the invention, the non-polar plane gallium nitride film is grown by plasma assisted molecular beam epitaxy. Since the growth environment is in a very high vacuum environment, the growth quality of the non-polar surface gallium nitride film is relatively small, and impurities such as oxygen or carbon are generated. In addition, the preferred embodiment of the present invention employs the m-plane sapphire substrate, which is easy to obtain a relatively large substrate size [about two turns], has a relatively low manufacturing cost, and has relatively high thermal stability and chemical stability. Most importantly, the preferred embodiment of the present invention does not require the step of growing a buffer layer or nitridation before growing the m-plane gallium nitride film. The preferred embodiment of the present invention can directly grow an m-plane gallium nitride film, which has the advantages of reducing epitaxial time and improving production efficiency.

The analysis of the non-polar surface gallium nitride film according to the preferred embodiment of the present invention by scanning electron microscopy [SEM] and electron backscattering instrument [RBS] shows that it can be changed while maintaining the same appropriate growth temperature. A growth condition for the ratio of nitrogen to gallium, wherein the ratio of nitrogen to gallium is selected to be 90, 80, 70 or other suitable ratio of nitrogen to gallium.

1a and 1b are schematic views showing the electron microscopic image and the atomic arrangement structure of a non-polar surface gallium nitride film grown on a sapphire substrate by a scanning electron microscope and an electron backscattering apparatus according to a preferred embodiment of the present invention. Referring to FIGS. 1a and 1b, when the predetermined ratio of nitrogen to gallium is 90, the surface of the m-plane gallium nitride film is rough and has a V-shaped crack, and the crack direction thereof is displayed according to the result of the electron backscattering device. In the c-direction of the m-plane gallium nitride, and in the out-of-plane direction, as shown in Fig. 1a, the crystal orientation is between the a-plane and the c-plane, as shown in Fig. 1b.

2a and 2b illustrate another schematic diagram of an electron microscopic image and an atomic arrangement structure of a non-polar surface gallium nitride film grown on a sapphire substrate by a scanning electron microscope and an electron backscattering apparatus according to a preferred embodiment of the present invention. . Referring to FIGS. 2a and 2b, when the predetermined ratio of nitrogen to gallium is 80, the surface of the m-plane gallium nitride film is rough and has a V-shaped crack mixed block shape in a straight strip shape. According to the results of the electron backscattering instrument, the block in the upper right box of Figure 2a is shown as a straight strip [labeled as A] and a V-shaped crack in the lower right box [labeled as B], and its crystal orientation is judged as m-plane. /a and c faces, as shown in Figure 2b.

3a and 3b are diagrams showing another embodiment of the preferred embodiment of the present invention for growing a non-polar surface gallium nitride film on a sapphire substrate to produce an electron microscopic image and an atomic arrangement by a scanning electron microscope and an electron backscattering device. . Referring to FIGS. 3a and 3b, when the predetermined ratio of nitrogen to gallium is 70, the surface of the m-plane gallium nitride film is strip-shaped; the crystal orientation is determined to be the m-plane and the stripe direction is the a-direction, as described in Figure 3b shows. In the invention, a m-plane gallium nitride film is directly deposited on the m-plane sapphire substrate by a plasma-assisted molecular beam epitaxy system, and the crystal orientation of the gallium nitride film can be changed by adjusting the predetermined ratio of nitrogen to gallium during growth.

The sapphire substrate of the preferred embodiment of the present invention has the advantages of relatively large area size, relatively low manufacturing cost, thermal stability, and relatively high chemical stability. The invention successfully obtains parameters for directly depositing an m-plane gallium nitride film on an m-plane sapphire substrate by using a molecular beam epitaxy system.

The foregoing preferred embodiments are merely illustrative of the invention and the technical features thereof, and the techniques of the embodiments can be carried out with various substantial equivalent modifications and/or alternatives; therefore, the scope of the invention is subject to the appended claims. The scope defined by the scope shall prevail.

A. . . Upper right box

B. . . V-shaped crack

1a and 1b are schematic views showing the electron microscopic image and the atomic arrangement structure of a non-polar surface gallium nitride film grown on a sapphire substrate by a scanning electron microscope and an electron backscattering apparatus according to a preferred embodiment of the present invention.

2a and 2b: another schematic diagram of the electron microscopic image and the atomic arrangement structure of the non-polar surface gallium nitride film grown on the sapphire substrate by a scanning electron microscope and an electron backscattering apparatus according to a preferred embodiment of the present invention .

3a and 3b are diagrams showing another embodiment of the preferred embodiment of the present invention for growing a non-polar plane gallium nitride film on a sapphire substrate to produce an electron microscopic image and an atomic arrangement by a scanning electron microscope and an electron backscattering apparatus. .

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Claims (8)

A method for growing a non-polar plane gallium nitride thin film on a sapphire substrate, comprising: providing a crystal plane on a sapphire substrate; and directly forming a non-polar surface nitride on the crystal plane of the sapphire substrate by a ratio of nitrogen to gallium a gallium film; wherein the non-polar plane gallium nitride film forms a light-emitting layer, and the non-polar plane gallium nitride film is directly formed on the sapphire substrate, and the non-polar plane gallium nitride film is changed by adjusting the ratio of nitrogen to gallium during growth. The crystal orientation; the ratio of nitrogen to gallium is 90, 80 or 70; when the ratio of nitrogen to gallium is 90, the surface of the non-polar plane gallium nitride film is rough and has a V-shaped crack, and the crack direction is m-plane nitride. The direction of c in gallium, and the crystal orientation is between the a-plane and the c-plane; when the ratio of nitrogen to gallium is 80, the surface of the non-polar plane gallium nitride film is rough and has a V-shaped crack mixed block shape and a straight strip The surface shape is determined by the m-plane/a-plane and the c-plane; when the ratio of the nitrogen to gallium is 70, the surface of the non-polar plane gallium nitride film is strip-shaped; the crystal orientation is determined to be m-plane and The stripe direction is the a direction. The method for growing a non-polar plane gallium nitride thin film on a sapphire substrate according to the first aspect of the patent application, wherein the crystal plane is an m-plane sapphire substrate, and the non-polar plane gallium nitride is directly deposited on the m-plane sapphire substrate. The film changes the crystal orientation of the non-polar plane gallium nitride film by adjusting the ratio of nitrogen to gallium during growth. The method for growing a non-polar plane gallium nitride film on a sapphire substrate according to the first aspect of the patent application, wherein the non-polar plane gallium nitride film is formed by plasma assisted molecular beam epitaxy. A method for growing a non-polar plane gallium nitride thin film on a sapphire substrate according to the first aspect of the patent application, wherein the crystal phase of the non-polar plane gallium nitride thin film is changed by adjusting a growth temperature thereof and a ratio of nitrogen to gallium. A light emitting diode structure for growing a non-polar plane gallium nitride film on a sapphire substrate, comprising: a sapphire substrate comprising a crystal face; and a non-polar surface gallium nitride film directly proportional to a nitrogen to gallium ratio Formed in the blue a non-polar surface gallium nitride film is formed on the crystal face of the gem substrate; the non-polar surface gallium nitride film is directly formed on the sapphire substrate, and the non-polar surface is changed by adjusting the ratio of the nitrogen to gallium during growth. a crystal orientation of the gallium nitride film; the ratio of nitrogen to gallium is 90, 80 or 70; when the ratio of nitrogen to gallium is 90, the surface of the non-polar plane gallium nitride film is rough and has a V-shaped crack, and the crack direction is The c-plane of the m-plane gallium nitride has a crystal orientation between the a-plane and the c-plane; when the ratio of the nitrogen-gallium is 80, the surface of the non-polar plane gallium nitride film is rough and has a V-shaped crack hybrid block. The surface shape of the straight strip is determined to be m-plane/a-plane and c-plane; when the ratio of nitrogen to gallium is 70, the surface of the non-polar plane gallium nitride film is strip-shaped; The m plane and the stripe direction are the a direction. a light emitting diode structure for growing a non-polar plane gallium nitride film on a sapphire substrate according to the fifth aspect of the patent application, wherein the crystal plane is an m-plane sapphire substrate, and the non-deposited non-deposited sapphire substrate is directly deposited on the m-plane sapphire substrate A polar surface gallium nitride film is formed by adjusting the ratio of the nitrogen to gallium during growth to change the crystal orientation of the non-polar plane gallium nitride film. The light-emitting diode structure of the non-polar surface gallium nitride film grown on the sapphire substrate according to the fifth aspect of the patent application, wherein the non-polar surface gallium nitride film is formed by plasma assisted molecular beam epitaxy. The light-emitting diode structure of the non-polar surface gallium nitride film grown on the sapphire substrate according to the fifth aspect of the patent application, wherein the non-polar surface gallium nitride film is changed by adjusting the growth temperature and the ratio of nitrogen to gallium Crystal phase.