Temperature-dependent photoluminescence of Ge/Si and Ge1-ySny/Si, indicating possible indirect-to-direct bandgap transition at lower Sn content

초록

Temperature (T)-dependent photoluminescence (PL) has been investigated for both p-Ge and n-Ge1-ySny films grown on Si substrates. For the p-Ge, strong direct bandgap (E-D) along with weak indirect bandgap related (E-ID) PL at low temperatures (LTs) and strong E-D PL at room temperature (RT) were observed. In contrast, for the n-Ge1-ySny, very strong dominant E-ID PL at LT and strong E-D PL were observed at RT. This T-dependent PL study indicates that the indirect-to-direct bandgap transitions of Ge1-ySny might take place at much lower Sn contents than the theory predicts, suggesting that these Ge1-ySny could become very promising direct bandgap semiconductors. (C) 2013 AIP Publishing LLC.

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