P-i-n photodetector with active GePb layer grown by sputtering epitaxy

In this paper, single-crystal GePb films were obtained by magnetron sputtering with high substrate temperature and rapid deposition rate. The GePb films have high crystalline qualities and smooth surfaces. The Pb content reached 1.29% and no segregation was observed. Based on this, a GePb-based p-i-n photodetector was successfully prepared. The device showed a room-temperature dark current density of 5.83 mA/cm2 at -1.0 V and a cutoff wavelength of 1990 nm, which covers all communication windows. At the wavelength of 1625 nm, responsivity of the photodetector reached 0.132 A/W at -1.0 V. The device demonstrates potential application in optical communications.