Performance of passivation layer for InP/InGaAs based short-wave infrared photodetector

The surface passivation effects of SiNx films deposited by plasma-enhanced chemical vapour deposition (PECVD) technique are investigated for InP/In0.53Ga0.47As mesa type photodetectors. It is found that the deposited SiNx film effectively reduces the densities of interface states (Dit) and slow trapped charge (Nt) near SiNx/In0.53Ga0.47As interface using NH4OH based pre-passivation treatment. The fixed charge density of 1.98 × 1011 C/cm2, the minimum value of Dit ∼3.2 × 1011 cm−2 eV−1 and Nt of 4.2 × 1011 C/cm2 are determined from the experimental capacitance-voltage curve of Ti–Au/SiNx/In0.53Ga0.47As based metal-insulator-semiconductor structure. Lower values of passivation properties indicate smaller surface recombination centre and lower surface leakage current. Thus, minimum noise related to dark current could be achieved for InP/In0.53Ga0.47As based mesa structured detector array with smaller pitch at room temperature.