Ge photodetector monolithically integrated on si by rapid-melting-growth technique

Germanium-based optoelectronic devices have the potential applications in optical communication and detections. In this letter, we demonstrated that high-quality Ge quasi-epilayer can be achieved by rapid-melting-growth and integrated-circuit compatible process. Raman and microscopy techniques revealed that the as-deposited Ge on the silicon substrate became quasi-single crystalline while nanocrystallites embedded within the Ge layer. The Ge/Si heterostructure photodetectors were fabricated with desirable responsivity of 0.22 A/W at -1 V reverse bias and the ratio of photocurrent and dark current is up to 2000 at -0.65 V. This technique demonstrated the possibility of monolithic integration of Ge photodetector for future optical communications at 1.31μm in wavelength with Si electronic circuitry.