Influence of the a-Si:H interfacial region defects on the quasi-static capacitance of Metal/c-Si/SiO2/a-Si:H structures

Metal/crystalline silicon/silicon dioxide/hydrogenated amorphous silicon structures (M/c-Si/SiO2/a-Si:H) are fabricated by thermal oxidation of n + doped crystalline Si followed by PECVD deposition of an a-Si:H film. The quasi-static capacitance-voltage (qs C-V) dependencies of the structures are measured using a modification of the standard qs C-V method, which allows reduction of the influence of a-Si:H transient currents. It is shown that the change in the qs C-V curve of the sample caused by thermal annealing with an applied bias can be explained using the defect-pool model for the defects in the a-Si:H. Therefore, the information obtained by qs C-V measurements can be used to characterize the defects close to the insulator/semiconductor interface in PECVD hydrogenated amorphous silicon.