JPS60175412A - Growing method of gallium nitride - Google Patents

Abstract

PURPOSE:To obtain a grown layer which has good surface flatness and crystallinity by performing the step of forming GaN on a crystalline substrate by the first step of executing in an inert atmosphere and the second step of performing in a hydrogen atmosphere. CONSTITUTION:The step of forming GaN on a crystalline substrate 4 is performed by the reaction of organic gallium compound with ammonia. In this case, the step is performed by the first step of executing in an inert atmosphere and the second step of performing in a hydrogen atmosphere. Organic gallium compound is selected from trimethyl gallium or triethyl gallium. Thus, a colorless, transparent, smooth-surface GaN crystalline layer is obtained on the substrate 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for growing gallium nitride (hereinafter referred to as GaN) on a crystal substrate by a reaction between an organic gallium compound and ammonia. It is.

Conventional configurations and problems GaN is seen as a promising semiconductor material for blue light-emitting devices, but large single crystals are difficult to produce, and it is usually prepared using a thermal decomposition method using an organic gallium compound and ammonia on a sapphire substrate. (hereinafter abbreviated as MOCvD method) is used. This MOCVD method is
Trimethyl gallium (hereinafter abbreviated as TMG) or triethyl gallium (hereinafter abbreviated as TEG) and ammonia (hereinafter abbreviated as NH3) are reacted in a gas phase, and the reaction product is placed on a sapphire substrate kept at a predetermined temperature. It grows crystals. In this crystal growth process, first, countless GaN nuclei are generated on the sapphire substrate, crystals gradually grow around these nuclei and become larger, and then adjacent crystal growths combine with each other to form a layered crystal body. is known to grow.

At this time, if hydrogen (H2) is used in the reaction atmosphere, the GaN nuclei generated in the initial stage will be large and have a low density.
The crystal growth proboscis that grows with this as a nucleus also becomes a large lump, and the layered crystal growth surface becomes a layered large rough surface. Further, this crystal has a high carrier concentration of 3×10 cm 2 and crystallinity does not improve easily. On the other hand, when the reaction atmosphere is an inert gas such as nitrogen (N2), argon (Ar), or helium (He), the initial product C2aN nuclei become fine and dense, but intermediates generated during the reaction process become The product is not decomposed and incomplete crystals containing methyl groups (-CH3) are formed in the grown crystals, resulting in extremely poor crystallinity.

Purpose of the Invention The present invention provides high-quality G on a crystal substrate by MOCVD method.
To provide a method for growing GaN that is capable of growing an aN crystal layer 〇Structure of the Invention To summarize, the present invention involves the process of producing GaN on a crystal substrate by the reaction between an organic gallium compound and ammonia. This is a GaN growth method in which the first step is carried out in an inert atmosphere, the second step is carried out in a hydrogen atmosphere, and a grown layer with good surface flatness and crystallinity is obtained. can get.

1. Explanation of Examples The drawing is a schematic cross-sectional view of the GaN crystal growth apparatus used in the implementation process of the present invention, and hereinafter, with reference to this drawing,
The present invention will be described in detail with reference to Examples.

In this device, a high-frequency induction heating source 2 is installed on the outer periphery of a quartz reaction tube 1 whose tube wall is cooled through cooling water, a carbon sussegrator 3 is installed inside the quartz reaction tube 1, and a sapphire single crystal is placed on top of the high-frequency induction heating source 2. Place the board 4 on the board 95
Heat and maintain at 0'C, connect upper pipe 5 to TMG and 6
Gas-phase reactions can be carried out by supplying N2 or N2 and NH3 from the same. In addition,
8 and 9 are respective flange parts, and 10 is a shaft part.

First, as the first step, approximately 72% of N2 is added to the reaction atmosphere.
Reactant gases NH3 and TMG are supplied at
They are introduced at a rate of 3β/min and 0.2 cc/min, respectively. In addition, 0.2cc/min of TMG is 1β/min N
2. Mix and supply. A reaction treatment is carried out for 10 minutes under these conditions.

Subsequently, as a second step, the atmosphere was reduced to 15&' N.
At the same time, the reaction gas TMG was also changed to 2 c
c/min mixed with 1 a/min of N2,
31 of NH3! , 7 minutes under gas conditions, 120 minutes and 114 hours. Through the above reaction treatment, a colorless and transparent G with a smooth surface is formed on the sapphire crystal substrate 4.
An aN crystal layer was obtained, and this GaN crystal had a carrier concentration of 6×100 and was of good quality.

Furthermore, surface observation of this GaN crystal layer confirmed that although it was a crystal with densely packed hexagonal pyramids, it did not have the sword-like protrusions seen in the conventional example and was smooth.

In this example, sapphire was used as the crystal substrate, but similar results can be obtained even if a silicon carbide (SiC) crystal substrate of the same crystal system is used.

Furthermore, in this example, the atmosphere N2 in the first step was changed to A
Even if r or He is substituted, almost the same result can be obtained.

In this example, even if TMG, which is the main reaction agent, is reacted with NH3 instead of TEG, the same results as in the case of TMG can be obtained.

Effects of the Invention According to the present invention, the growth of a C1aN crystal using the MOCVD method changes the atmospheric condition from an inert atmosphere to a hydrogen atmosphere in the first stage of GaN nucleus generation and the second stage of crystal formation. By changing the crystal layer, a stable and high quality crystal layer can be realized. The GaN crystal obtained by this method is
It is highly practical as a material for blue light emitting elements,
It is promising for industrialization.

[Brief explanation of the drawing]

The drawing is a schematic cross-sectional view of a GaN crystal growth apparatus used in an example of the present invention. 1...Quartz reaction tube, 2...High frequency induction heating source, 3...Carbon the receptor, 4...
・The 7 Aia single crystal substrate, 5, 6, 7... Gas piping, 8, 9... Flange part, 10. Old... Shaft part.

Claims (3)

[Claims] (1) The process of producing gallium nitride on a crystal substrate by the reaction between an organic gallium compound and ammonia is performed in the first step in an inert atmosphere and the second step in a hydrogen atmosphere. How to grow gallium nitride,) (2) The method for growing gallium nitride according to claim 1, wherein the organic gallium compound is selected from trimethylgallium or triethylgallium. (3) The method for growing gallium nitride according to claim 1, wherein the inert atmosphere is selected from nitrogen, argon, or helium.