Some critical issues on structural and photovoltaic properties of Ge/Si heterojunction

We report the structural and photovoltaic (PV) characteristics of heteroepitaxial Ge film on monocrystalline Si (111). The influence of Ge thickness and two types of annealing conditions on Ge/Si heterostructure and PV parameters have been investigated. The experimental data exhibit that the structural defects have been reduced after annealing. On the other hand, significant improvement in PV characteristics after annealing was obtained. The results of VOC and JSC after classical thermal annealing (CTA) at 500 °C for 20 min were 430 mV and 15 mA/cm2, respectively, while for rapid thermal annealing (RTA) at 500 °C/25 s) VOC = 360 mV and JSC = 5 mA/cm2 under AM1 simulating conditions were obtained. Photoresponsivity investigation in spectral range (0.7–1.3) μm has been carried out for Ge/Si heterojunctions before and after annealing.