Process for producing laminate comprising Al-based group III nitride single crystal layer, laminate produced by the process, process for producing Al-based group III nitride single crystal substrate using the laminate, and aluminum nitride single cry

Abstract

Disclosed is a process for producing a laminate, comprising (1) the step of providing a base substrate having a surface formed of a single crystal of a material different from a material for constituting an Al-based group III nitride single crystal layer to be formed, (2) the step of forming an Al-based group III nitride single crystal layer having a thickness of 10 nm to 1.5 mum on the single crystal plane of the provided base substrate, (3) the step of forming a non-single crystal layer having a thickness of not less than 100 times the thickness of the Al-based group III nitride single crystal layer on the Al-based group III nitride single crystal layer without breaking the Al-based group III nitride single crystal layer, and (4) the step of removing the base substrate. The production process can provide a substrate that is suitable for use as a base substrate for the production of a self-supporting substrate of an Al-based group III nitride single crystal, has a surface formed of a single crystal of an Al-based group III nitride, and is free from cracking and warpage.

Description

technical field [0001] The present invention relates to a method for producing a substrate composed of a single crystal of an Al-based group III nitride such as aluminum nitride. Background technique [0002] Aluminum nitride (AlN) is expected to contain a mixture of AlN, gallium nitride (GaN) and indium nitride (InN), which are also group III nitrides, because of its high forbidden band width of 6.2 eV and a direct transition type semiconductor. In particular, mixed crystals (hereinafter also referred to as Al-based group III nitride single crystals) in which the proportion of Al in group III elements is 50 atomic % or more are used as materials for ultraviolet light emitting elements. [0003] In order to form a semiconductor element such as an ultraviolet light emitting element, a laminated structure including a cap layer, an active layer, etc. must be formed between the n-type semiconductor layer electrically bonded to the n electrode and the p-type semiconductor layer e...

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Problems solved by technology

Among them, the HVPE method is difficult to precisely control the film thickness compared with the MOVPE method and the MBE method. Therefore, although it is not suitable for the formation of a crystal layered structure of a semiconductor light-emitting element, it can obtain a single layer with good crystallinity at a fast film formation rate. crystal, so the HVPE method is frequently used in vapor deposition for the purpose of forming a single crystal thick film

[0005] However, when forming group III nitride single crystals such as GaN, including Al-based group III nitride single crystals, by vapor deposition, it is difficult to prevent lattice mismatch between the substrate and the deposited group III nitrides. Dislocations arising from the interface

Furthermore, since deposition is performed at a high temperature close to 1000°C, when depositing a thick film, the difference in thermal expansion coefficient with the substrate causes problems such as warpage after deposition, increase of dislocations due to deformation, crack cracking, etc.

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