Surface photovoltage spectroscopy (SPS) was used to determine the electronic structure of hydrogenated transition Si films. All samples were prepared by using a helicon wave plasma-enhanced chemical vapour deposition technique. The films exhibited a transition from the amorphous phase to the microcrystalline phase with increasing temperature. The film deposited at lower substrate temperatures had an amorphous-like electronic structure with 2 types of predominant defect state corresponding to the occupied Si dangling bond states (D0/D−) and the empty Si dangling states (D+). At higher substrate temperatures, the crystallinity of the deposited films increased, while their band-gap energy decreased. Meanwhile, two types of additional defect states were incorporated into the films as compared with the amorphous counterpart, which was attributed to the interface defect states between the microcrystalline Si grains and the amorphous matrix. The relative SPS intensity of these two kinds of defect state in samples deposited above 300C increased first and decreased afterwards, which could be interpreted as being a result of the competition between hydrogen release and crystalline grain size increment with increasing substrate temperature.

Electronic Structure and Defect States of Transition Films from Amorphous to Microcrystalline Silicon Studied by Surface Photovoltage Spectroscopy. W.Yu, C.H.Wang, W.B.Lu, J.He, X.X.Han, G.S.Fu: Chinese Physics, 2007, 16, 2310-4