Material Defects and Dark Currents in InGaAs/InP Avalanche Photodiode Devices

An In 0.53 Ga 0.47 As/indium phosphide (InP) avalanche photodiode (APD) with a separate absorption, grading, charge, and multiplication (SAGCM) structure is epitaxially grown by molecular beam epitaxy (MBE). The resulting material is studied using X-ray diffraction (XRD), photoluminescence (PL), and scanning transmission electron microscopy. The activation energy extracted from the dark current of the APD indicates that it is dominated by the generation-recombination (G-R) process. Deep low-temperature PL peaks reveal the existence of an {E}_{v} + 0.42 -eV deep energy level defect in the indium-gallium-arsenide (InGaAs) absorber layer, which is considered to be a result of point defects caused by Ga-poor or In-poor MBE growth conditions. The effect of the defect on the dark current is confirmed using numerical calculation methods.