Evaluation of SiC as a substrate material for nitride materials heteroepitaxy

We present a methodology based on the elasticity theory of strained interfaces to optimize semiconductor heterointerfaces. For GaN heteroepitaxy, an alternative to sapphire substrate can be provided by SiC, which offers a better lattice matching and closer thermal expansion properties. The choice of AlN as an optimizing buffer layer material is interesting because AlN and SiC have similar physical properties. We have recently shown that the evaluation of host materials for heteroepitaxy must be based not only on geometric parameters of the host materials, but also on such parameters involving dynamics and interface strain features as identified from the equations of the elasticity theory which correlates lattice dynamics and strain gradients via the effective elastic constants and atomic density parameters (S factor) of the host materials. We demonstrate that, when AlN is used as a buffer layer, the heteroepitaxy of GaN can be optimized. These theoretical results show that the SiC-substrate alternative with the use of AlN, is a valuable approach for optimizing GaN heteroepitaxy.