Carrier Mobility Model of DR-Ge_1–x Sn _x for Monolithic Same Layer Optoelectronic Integration

Direct bandgap relaxed GeSn is widely used in LED optical devices due to its high carrier radiation efficiency, and it is expected to be applied in monolithic same layer photovoltaic integration if the mobility further improved. However, the current carrier mobility model of direct bandgap relaxed GeSn is still imperfect, which limits the practical application in MOS and monolithic same layer photovoltaic integrated devices. In this paper, we studied the E-k relation of energy band, and established the quantitative analytical model of carrier mobility. Especially, the results of the energy band structure and carrier mobility model were verified by Photoluminescence Spectroscopy and Monte Carlo simulation. The results show that: (1) compared with pure Ge, the electron mobility of direct bandgap relaxed GeSn has doubled; (2) the hole mobility is slightly lower than that of pure Ge, but still 3 times of that of Si; (3) since hole mobility anisotropy exists in crystal, [100] orientation should be chosen in PMOS devices due to its highest hole mobility. Our results could provide a valuable reference to the design of GeSn monolithic same layer optoelectronic integrated devices.