Efficient relaxation of strained-SiGe layers induced by thermal oxidation

Abstract

The new route to fabricate compositionally graded and highly-relaxed Si 1-xGe x layers using thermal oxidation at high temperatures is investigated. Ge atoms behavior during thermal oxidation of Si 1-xGe x layers is strongly dependent on the oxidation temperature. For low temperature oxidation processes Ge is incorporated as GeO 2 in the grown oxide layer, while for higher temperatures it accumulates below the grown oxide into a layer with a higher concentration than the initial Si 1-xGe x. However, Si 1-xGe x layers oxidized at 1000 °C did not show such an accumulation layer because Ge diffusion efficiently occurred, resulting in the formation of a compositionally graded and relaxed Si 1-xGe x layer. Such layers could be used as virtual substrates for the strained-Si and relaxed-SiGe applications.