Distorted wurtzite unit cells: Determination of lattice parameters of nonpolar a-plane AlGaN and estimation of solid phase Al content

摘要: Unlike c-plane nitrides, “nonpolar” e.g., those grown in the a-plane or m-plane orientation encounter anisotropic in-plane strain due to anisotropy lattice and thermal mismatch with substrate buffer layer. Such results a distortion of wurtzite unit cell creates difficulty accurate determination parameters solid phase group-III content (xsolid) ternary alloys. In this paper we show that is orthorhombic, outline relatively simple procedure for measurement nonpolar group III-nitrides epilayers from high resolution x-ray diffraction measurements. We derive an approximate expression xsolid taking into account strain. illustrate using data AlGaN, where measure estimate Al content, also method applicable structures as well.