III-V group nitride system semiconductor self-standing substrate, method of making the same and III-V group nitride system semiconductor wafer

Abstract

A III-V group nitride system semiconductor self-standing substrate is made of III-V group nitride system semiconductor single crystal with a hexagonal crystal system crystalline structure. The substrate is provided with a surface that is off-oriented 0.09 degrees or more and 24 degrees or less in the a-axis or m-axis direction from C-face of the substrate.

Description

[0001] The present application is based on Japanese patent application No. 2004-162189, the entire contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a III-V group nitride system semiconductor self-standing substrate, a method of making the same, a III-V group nitride system semiconductor wafer. [0004] 2. Description of the Related Art [0005] Nitride system semiconductor materials such as gallium nitride (GaN), indium gallium nitride (InGaN) and gallium aluminum nitride (GaAlN) have a sufficiently wide bandgap and are of direct transition type in inter-band transition. Therefore, they are a great deal researched to be used for short-wavelength light emitting devices. Further, they have a high saturation drift velocity of electron and can use two-dimensional carrier gases in hetero junction. Therefore, they are also expected to be used for electronic devices. [0006] With silicon ...

AI Technical Summary

Benefits of technology

[0016] It is a further object of the invention to provide a method of making the III-V group nitride system semiconductor self-standing substrate that has a predetermined off-angle with a good reproducibility.

[0017] It is a further object of the invention to provide a III-V group nitride system semiconductor wafer that a III-V group nitride system semiconductor layer is homo-epitaxially grown on the self-standing substrate with good flatness, uniformity and reproducibility.

[0036] It is advantageous that the III-V group nitride system semiconductor self-standing substrate of the invention can offer an epitaxial growth layer with high flatness, uniformity and reproducibility when epitaxially growing a nitride system semiconductor layer on the self-standing substrate.

[0037] Further, it is advantageous that the method of making a III-V group nitride system semiconductor self-standing substrate of the invention can offer a III-V group nitride system semiconductor substrate with a suitable off-orientation with a good reproducibility while combining simple processes each not different from a known substrate manufacturing process.

[0038] Further, it is advantageous that the III-V group nitride system semiconductor wafer of the invention can provide, on the self-standing substrate, an epitaxial growth layer with high flatness, uniformity and reproducibility. Therefore, the production yield in both epitaxial growth process and device fabrication process can be enhanced. In addition, a light-emitting device or electronic device can be produced with characteristics as designed.

Problems solved by technology

On the other hand, it is difficult to grow a bulk crystal of nitride system semiconductor, and a GaN self-standing substrate did not exist before the epitaxial growth of nitride is researched.

However, in the hetero-epitaxial growth on hetero-substrate, a number of dislocations (defects) must be generated in grown crystal due to a lattice mismatch between the underlying substrate and the grown crystal.

However, even when such a GaN self-standing substrate is used to grow a GaN system epitaxial layer thereon, it is difficult to flatten its surface morphology in the epitaxial growth while offering high flatness, uniformity and reproducibility.

However, it is unknown what off-direction and how much off-angle of GaN self-standing substrate is proper in growing epitaxially a nitride system semiconductor layer.

Further, even when a proper off-angle is found, the GaN self-standing substrate with the proper off-angle cannot be made with a good reproducibility since it is still made by separating a thick crystal grown hetero-epitaxially from the hetero-substrate, different from the case of a GaAs substrate that a wafer can be cut off from an ingot grown as a bulk crystal.

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