Optical absorption spectra of a-Si:H MIS structure measured by transient photocapacitance spectroscopy

The transient photocapacitance spectroscopy (TPC) was applied to measure the optical absorption spectra of hydrogenated amorphous silicon (a-Si:H) in metal-insulator-semiconductor (MIS) structure. The measured spectra show the features of optical transitions from both D0 and D− defect bands to conduction band. The stability of measurement was checked against the change of probe frequency. The availability of TPC in detecting the defect density changes was also tested by checking the well-known defect density increase in a-Si:H after light illumination.