Temperature dependence of the photocurrent in Ge 1− x Sn x layers

The temperature dependence of the photocurrent in Ge 1− x Sn x layers was measured for different Sn compositions (0.00 ≤ x ≤ 0.83%). As the Sn composition in the Ge 1− x Sn x layer increased, the photocurrent peak was clearly red shifted in comparison with that of Ge. As the measurement temperature was increased, the photocurrent peak was also clearly red shifted. The measured temperature dependence of the energy band gap was nicely fitted by using Varshni’s empirical expression. Temperature-dependent bowing parameters were fitted for the equation relationship.