Doping of Direct Gap Ge_1-ySn_y Alloys to Attain Electroluminescence and Enhanced Photoluminescence

Low temperature (T < 300°C) in-situ doping protocols were developed for Ge_1-ySn_y alloys with compositions above the indirect-to-direct gap crossover point, which were deposited using CVD. Trisilylphosphine (P(SiH₃)₃) was used as the n-type dopant source while diborane (B₂H₆) was used for n-type doping. This enabled the fabrication of pin diode structures with compositions up to y = 0.137. These photodiodes exhibit electroluminescence at wavelengths up to 2700 nm. Furthermore, it was demonstrated that n-type doping enhances the photoluminescence obtained from these materials.