Scanning capacitance microscopy investigation on InGaAs/InP avalanche photodiode structures: Light-induced polarity reversal

Abstract

Cross-sectional scanning capacitance microscopy is applied to study the carrier distribution as well as its variation under irradiation in an InGaAs/InP avalanche photodiode. The photocarriers excited by the stray light of atomic force microscope laser beam lead to a dramatic deviation of the dC/dV profile in the unintended-doped absorption layer, and even cause the reversal of signal polarity. The existence of surface potential and its impact on the spreading of photocarriers near the cleaved face are demonstrated as the main origins of the light-induced dC/dV reversal. The effect provides experimental information on the distribution property of photoelectric process in devices.