Abstract
Amorphous semiconductor bilayers composed of hydrogenated amorphous silicon (a-Si:H) and hydrogenated fluorinated amorphous silicon carbide (a-Sic: H: F) have been characterized with respect to the interface structure and the valence-band discontinuity using in situ X-ray photoelectron spectroscopy (XPS). XPS of the core levels C 1s, F 1s and Si 2p and of the valence band was carried out for two types of bilayer specimen. These were obtained by depositing a-Si: H of various thicknesses onto 20 nm of a-SiC: H: F by two different methods: a batch method using conventional gas exchange and a continuous method using excitation energy exchange. An analysis of the intensity associated with photoelectrons emitted from the C 1s and F 1s core levels in the a-SiC:H:F and passing through the a-Si:H overlayer indicates that the interface fabricated by the batch process is ideally sharp and that by the continuous method has a compositional transition region about 0.5 nm thick. The valence-band offset was determined to be 0–6 eV.