Surface passivation and capping of GaSb photodiode by chemical bath deposition of CdS

Abstract

A cadmium sulfide thin film deposited by a chemical bath deposition technique has been found to act as a passivating layer and a capping layer for GaSb photodiodes. X-ray photoelectron spectroscopy analysis shows the presence of Ga–S and Sb–S bonds along with the cadmium binding energies. Reduction in the reverse leakage current after the passivation is accompanied by a significant increase in the zero bias resistance-area product (14.29–100Ωcm2). In addition, the dependence of the zero bias resistance-area product on the device dimension reduced considerably. There was no degradation in the dark current performance over a period of 3months, indicating long-term stability.