X-ray photoelectron spectroscopy study of band offsets in a-Si_0·2C_0·8:H/p-(a-Si:H) and a-Si_0·2C_0·8:H/n-(a-Si:H) heterojunctions

Abstract

Valence-band offsets ΔE_v have been evaluated from an X-ray photoelectron spectroscopy (XPS) study of heterojunctions of a-Si_0·2C_0·8:H/p-(a-Si:H) and a-Si_0·2C_0·8:H/n-(a-Si:H). The values of ΔE_v for a-Si_0·2C_0·8:H/p-(a-Si:H) heterojunctions are estimated to range from 1·2 ± 0·05 to 1·5 ± 005 eV depending on the amounts of dopant in the a-Si:H. For a-Si_0·2C_0·8:H/n-(a-Si:H), ΔE_v is 0·7 ±005eV. The origin of the difference in the values for different types and levels of doping in a-Si: H is discussed. Reported electron transport properties are discussed using the band structure at the hetero-interfaces obtained from the present XPS study.