Single-crystal – oriented-crystal – and epitaxy growth processes; – Forming from vapor or gaseous state – With decomposition of a precursor
Patent
1995-12-06
1998-02-10
Kunemund, Robert
Single-crystal, oriented-crystal, and epitaxy growth processes;
Forming from vapor or gaseous state
With decomposition of a precursor
117952, 117902, 117 88, C30B 2300
Patent
active
057164509
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of growing a gallium nitride related compound semiconductor crystal, and more particularly, to a method of growing a gallium nitride related compound semiconductor crystal suitable for blue light emitting materials and excellent in crystallinity, and a gallium nitride related compound semiconductor device.
BACKGROUND ART
Recently, notice is focused on gallium nitride related compound semiconductors (In.sub.x Ga.sub.y Al.sub.1-x-y N) (0.ltoreq.x, y; x+y.ltoreq.1) as blue light emitting materials.
In the case where gallium nitride related compound semiconductor crystal is grown on a sapphire (.alpha.-Al.sub.2 O.sub.3) substrate, there are many cases in which the gallium nitride related compound semiconductor crystal with the (0001) plane is grown on the (0001) plane of the sapphire. In this case, the lattice mismatch is up to 16% and, therefore, it was impossible to grow a gallium nitride related compound semiconductor crystal with good quality.
For this reason, in order to solve the problem, the following two methods were proposed as a method of growing a gallium nitride related compound semiconductor crystal: and a buffer layer is first grown for the purpose of relaxation of lattice mismatching between the sapphire substrate and the gallium nitride related compound semiconductor crystal, and then the gallium nitride related compound semiconductor crystal is grown; and compound semiconductor in the crystal structure and lattice constant as close as possible, is used as a substrate.
As the first method are known a method (Japanese Patent Application Publication (Examined) No. Tokuko-Sho 59-48794) in which an AlN buffer layer is used and a method (Japanese Patent Application Publication (Laid-Open) No. Tokukai-Hei 4-297023) in which a GaAlN buffer layer is used.
Certainly, by introducing these buffer layers, the crystallinity and surface morphology of the gallium nitride related compound semiconductor crystal is improved to some extent. However, since the gallium nitride related compound semiconductor crystal inevitably has the lattice mismatching to the sapphire substrate, the crystal is still in the distorted state. For this reason, in the case of using such crystal to produce a light emitting device, there is a problem that significant improvement in brightness cannot be obtained and the lifetime is short.
In the second method, there are known a method (Japanese Patent Application Publication (Laid-Open) No. Tokukai-Sho 49-3899) in which aluminium garnet (ReAl.sub.2 Al.sub.3 O.sub.12) or gallium garnet (ReAl.sub.2 Ga.sub.3 O.sub.12) is used as a substrate, and a method (Japanese Patent Application Publication (Laid-Open) No. Tokukai-Hei 4-209577) in which MnO, ZnO, MgO, CaO etc. are used as a substrate. However, for aluminium garnet or gallium garnet whose lattice constant falls in a range of 12.00 to 12.57 .ANG., the lattice distance of (111) plane only corresponds to the fifth times a axis of GaN and therefore the lattice matching is not necessarily good.
Further, although the lattice matching is good in MnO, ZnO, MgO, CaO, etc., these oxides are weak in heat. Accordingly, in the case of growing gallium nitride related compound semiconductor crystal, which is required to grow at high temperature of about 1000.degree. C., there is a problem that the substrate is subjected to thermal decomposition and a gallium nitride related compound semiconductor crystal layer with good quality cannot be obtained.
DISCLOSURE OF THE INVENTION
The present invention is made to solve such problems and an object of the present invention is to provide a method of growing a gallium nitride related compound semiconductor crystal with high quality suitable for blue light emitting material and gallium nitride related compound semiconductor device by using a single crystal substrate with relatively good lattice matching to the gallium nitride related compound semiconductor crystal and stable under the growing condition of the gallium nitride related compound semicond
REFERENCES:
patent: 4855249 (1989-08-01), Alasaki et al.
patent: 5290393 (1994-03-01), Nakamura
Haisma et al., "Lattice Constant-Adaptable Crystalographics", Journel of Crystal Growth, vol. 100, No. 4, Jun. 1990.
Hisaki Kato et al., Journal of Crystal Growth, MOVPE growth of GaN on a . . . , vol. 107, No. 1/4, Jan. 1991, pp. 509-512.
Okazaki Hitoshi
Togawa Seiji
Japan Energy Corporation
Kunemund Robert
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