Fabrication of PIN photo-diode from p-Ge/i-Ge/n-Si hetero junction structure

A pin photo-diode was fabricated from the p-Ge/i-Ge/n-Si hetero junction structure grown by using rapid thermal chemical vapor deposition (RTCVD). The structural properties of the p-Ge/i-Ge/n-Si hetero junction structure were investigated using high-resolution X-ray diffraction (HRXRD). Specifically, the recent advances in the dry etching of p-Ge/i-Ge/n-Si hetero junction structure have been used to define pin photo-diode p-Ge/i-Ge layer mesas. I-V characteristics of the pin photo-diode indicate a reasonable reverse saturation current of 96 μA at -1 V and a high reverse breakdown voltage in excess of -100 V. The photocurrent with a responsivity of 0.19 A/W at the wavelength of 1.55 μm is flat over a wide range of reverse bias voltage and the leakage currents is 700 nA at a reverse 0.1 V bias voltage. The roll-off in photocurrent spectra after wavelength of 1600 nm is expected due to the decreased absorption of Ge at room temperature.