Method for heterogeneously growing AlN on SiC seed crystal via PVT (physical vapor transport) process

Abstract

The invention discloses a method for heterogeneously growing AlN on a SiC seed crystal via a PVT process. The method comprises the following steps: designing a crucible structure comprising a vapor saturation microcavity, wherein vacuumizing and inflating can be conducted in the microcavity; in an initial growth stage of AlN, inhibiting forward decomposition and sublimation of initial SiC and realizing growth of AlN by adopting the vapor saturation microcavity, inhibiting lateral sublimation of the initial SiC by covering of an adhesive with weak air holes, and allowing an AlN polycrystalline spacer to gradually sublimate from the back and to be deposited on the surface of the SiC; after sublimation of the polycrystalline spacer disappears, transporting Al atoms obtained by sublimation at AlN source powder to a growth surface; and after the AlN polycrystalline spacer and the AlN adhesive sublimate, allowing an AlN layer to cover the SiC seed crystal, and enabling the AlN adhesive on the side surface of the SiC to sublimate to leave a crucible area, thereby realizing lateral sublimation and decomposition of the SiC and gradual disappearing of the SiC seed crystal layer and obtaining the SiC-free AlN seed crystal. By adopting the method disclosed by the invention, the crack-free AlN seed crystal with high single crystal rate and low impurity content can be prepared.

Description

technical field [0001] The invention relates to the technical field of crystal growth, in particular to a method for heterogeneously growing AlN on a SiC seed crystal by using a physical vapor transport method (PVT method). Background technique [0002] The lattice mismatch and thermal mismatch between AlN (aluminum nitride) and high Al composition AlGaN (aluminum gallium nitride) are very small, and high-quality AlN single crystal can be used as a homogeneous or near-homogeneous epitaxial substrate, which can significantly Reduce the dislocation density of the epitaxial layer to improve the lattice quality. Therefore, AlN single crystal has become the optimal substrate for the epitaxial growth of AlN and AlGaN structures to make deep ultraviolet optical elements. At the same time, AlN single crystal has many excellent properties, including high breakdown field strength, high thermal conductivity, high hardness, excellent electrical properties, etc., and is one of the import...

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Problems solved by technology

[0004] In order to overcome the above-mentioned problems in the prior art, the present invention provides a new method for heterogeneously growing AlN on SiC seed crystals by physical vapor transport method (PVT method), which is a bonding method using vapor-saturated microcavity and AlN AlN powder (the main component is AlN powder, which can be sublimated similar to AlN source powder) inhibits the initial decomposition and sublimation of SiC while promoting the middle and late sublimation of SiC to prepare the growth technology of large-sized AlN seed crystals, which can significantly improve the heterogeneous growth on SiC single crystals The existing methods of obtaining AlN seed crystals with the same size have problems such as low single crystal rate of AlN seed crystals, high impurity content, poor crystal quality and cracks

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