Sub-bandgap photo-response of Mo-hyperdoped black silicon MSM photodetectors

The molybdenum-hyperdoped black silicon materials were fabricated by using femtosecond laser pulses. The energy level of molybdenum in bandgap of silicon was determined by temperature-dependent Hall effect measurements. By introducing intermediate band in the bandgap of silicon, molybdenum-hyperdoped black silicon materials showed thermally stable absorption to photons with energy below the bandgap of silicon (0.5–1.1 eV). We studied current–voltage characteristics of metal-black silicon-metal photodetectors prepared using molybdenum hyperdoped black silicon. The lateral structural photodetectors showed an observable photo-response to the infrared photon. The room-temperature responsivity of 25.1 mA/W at 0.95 eV was obtained.