Abstract
We report a theoretical investigation of strained Ge1-xSnx/Ge (001)-oriented quantum wells as a bulding block in active region of infrared photodetector. The electronic band parameters, gaps, discontinuities and effective masses for heterointerfaces between compressively strained Ge1-xSnx and relaxed Ge have been computed at room temperature. From this preliminary and mendatory work, we conclude that pseudomorphic Ge1-xSnx alloys become direct band gap semiconductors at a Sn-fraction of 15.3%, e.g. a lattice mismatch as high as 2.3%. Due to achievable critical layer thickness and mainly solid solubility limit, a type-I compressively strained Ge/Ge0.92Sn0.08/Ge (double) quantum well is studied by solving Schrodinger equation without and applied bias voltage. A strong absorption coefficient (>1x10(4) cm(-1)) and a Stark shift of the direct transition between 2.01 mu m and 2.25 mu m at large external fields (40kV/cm) are attractive characteristics for the design of infrared photodetectors (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim