Investigation of the plasma deposited silicon dioxide on hydrogenated amorphous silicon interface by capacitance measurements

Abstract

The authors report on the investigation of the interface between plasma-deposited SiO2 (silicon dioxide) and a-Si:H (hydrogenated amorphous silicon), and compare the results with those of the SiO2 on crystalline silicon interface. They attribute the fixed charge in the SiO2 deposited on crystalline silicon to the trapping of holes from the silicon substrate in the insulator that occurs during the deposition process. However, the trapping of holes can be prevented if an a-Si:H layer is deposited prior to the insulator deposition. Finally, they show evidence for a large number of interface states at energies less than 0.35 eV below the a-Si:H conduction band.