バイメタルモデルによる基板エピタキシャル層間格子定数差の測定

概要

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A bimetallic model is proposed in measurement of very small difference rate of lattice constant Δa/a between epitaxial layer and the substrate of the epitaxial layer/substrate structure. It is predicted theoretically that Δa/a of the specimen can be measured up to the order of 10^<-7> by this method, if the epitaxial layer is thicker than 3μm. The method is applied to non-doped GaAs epitaxial layer / Cr-doped GaAs substrate structure. Δa/a of the specimen is 1.7×10^<-6> and the lattice constant of the non-doped GaAs is slightly larger than that of Cr-doped GaAs. The concentration of Cr (9.4ppm) obtained from this lattice constant difference does not agree with the doping concentration of Cr(0.1-0.5ppm) in the substrate. This suggests that some other lattice defects are contained in the specimen. The method can not be appled to the specimen with the scratched surface, because such specimen warps abnormally with reducing the thickness.
琉球大学工学部の論文