Germanium p-i-n avalanche photodetector fabricated by point defect healing process

In this Letter, we report Ge p-i-n avalanche photodetectors (APD) with low dark current (sub 1 mu A below V-R = 5 V), low operating voltage (avalanche breakdown voltage = 8-13 V), and high multiplication gain (440-680) by exploiting a point defect healing method (between 600 degrees C and 650 degrees C) and optimizing the doping concentration of the intrinsic region (p-type similar to 10(17) cm(-3)). In addition, Raman spectroscopy and electrochemical capacitance voltage analyses were performed to investigate the junction interfaces in more detail. This successful demonstration of Ge p-i-n APD with low dark current, low operating voltage, and high gain is promising for low-power and high-sensitivity Ge PD applications. (C) 2014 Optical Society of America