A modification of usual C–V measurement to more precisely characterize the band offsets in a-Si:H/c-Si heterojunctions

Due to a strong inversion layer at the a-Si:H/c-Si interface, there are errors in the determination of the band offsets by usual capacitance–voltage (C–V) measurements. An improved C–V measurement was presented to correct the errors by a modification to the apparent diffusion potential Vint. In this paper, the improved C–V measurement is used to characterize the band offsets in a-Si:H/c-Si heterojunctions with a good precision. The modified apparent diffusion potential is determined from Vint and the minority carrier density at the c-Si interface deduced from the coplanar conductance measurements. The value of ΔEC = 0.17 ± 0.04 eV between a-Si:H and c-Si is found by the improved C–V measurement with a precise determination of the band offsets.