Study of GePb photodetectors for shortwave infrared detection

Ge_0.998Pb_0.002 photodetectors (PDs) with a GePb layer grown on n-type Ge (100) substrate by magnetron sputtering epitaxy were fabricated by complementary metal-oxide semiconductor (CMOS)-compatible technology. For Ge_0.998Pb_0.002 PDs, the room-temperature dark current density at -1 V was 3.3 A/cm². At room temperature, the GePb PDs demonstrated a longwave cutoff of 2.5 μm and the optical responsivities of GePb PDs ranging from 1500 nm to 2000 nm were measured. A temperature dependence optical characterization of these detectors was conducted and temperature-dependent energy bandgaps of Ge_0.998Pb_0.002 were derived from the photocurrent spectra.