Abstract
A GexSn1-x/Ge quantum well structure is studied by the 8-band k.p method. The band structures of both direct Γ valley and indirect L valley were calculated, and the relations between temperature and the spontaneous emission rate spectrum (SERS) were investigated. The results show an abnormal temperature dependent SERS phenomenon in the so-called pseudo-direct gap semiconductor. This can be explained by taking consideration of the contribution of electrons in the indirect L valley injecting into direct Γ valley under a higher temperature. Cases of higher Sn composition accompanied with larger compressive strain were investigated using the same model. The significant compressive strain effect compensates the dragging down of energy gap by the induced Sn atoms, which makes it difficult to achieve the transition from indirect band-gap material to direct band-gap material in quantum well devices.
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