THz characterization of GeSn monocrystalline thin films

The employment of other group IV materials, such as alloys of germanium and tin, poses a solution for overcoming the efficiency limit of silicon that arises from its indirect bandgap. By using THz spectroscopy, the optoelectronic properties, such as conductivity, mobility, carrier lifetime, can be extracted noninvasively, since there is no electrical contact. In this work, we use optical pump-THz probe (OPTP) spectroscopy to examine the photoconductivity lifetime and mobility of GeSn alloy thin film samples with different Sn concentration. The results demonstrate photoconductivity lifetimes on nanosecond timescales and carrier mobilities in range of 40 similar to 210cm(2)/(Vs), highlighting the promise of these thin films in device applications.