Evaluation of SiC as a substrate material for nitride materials heteroepitaxy

We present a methodology based on the elasticity theory of strained interfa ces to optimize semiconductor heterointerfaces. For GaN heteroepitaxy, an a lternative to sapphire substrate can be provided by SiC, which offers a bet ter 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 evalu ation of host materials for heteroepitaxy must be based not only on geometr ic 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 gradient s via the effective elastic constants and atomic density parameters (S fact or) of the host materials. We demonstrate that, when AlN is used as a buffe r layer, the heteroepitaxy of GaN can be optimized. These theoretical resul ts show that the SiC-substrate alternative with the use of AlN, is a valuab le approach for optimizing GaN heteroepitaxy. (C) 2001 Elsevier Science B.V . All rights reserved.