Characterization of amorphous-crystalline silicon heterojunctions using constant photocurrent method |
Posted on:2007-06-25 | Degree:M.A.Sc | Type:Thesis |
University:University of Toronto (Canada) | Candidate:Bahardoust, Barzin | Full Text:PDF |
GTID:2451390005990968 | Subject:Electrical engineering |
Abstract/Summary: | |
Amorphous-crystalline silicon (a-Si:H/c-Si) heterojunctions have recently drawn much attention owing to their low-temperature fabrication and high-efficiency photovoltaics. a-Si:H/c-Si heterojunctions were studied for the first time using the constant photocurrent method (CPM). The doping concentration in the p-type a-Si:H was varied. CPM derived absorption for energies greater than 1.4 eV is observed to increase with decreasing dopant concentration in the p- layer. This is attributed to a decrease in the density of defect states in the amorphous layer and the interface. A model is proposed wherein the amorphous layer and the interface constitute one absorbing layer while the crystalline substrate forms the other absorbing layer. A combined defect density in the amorphous layer and interface of 2.8x1018 cm-3 eV-1 at 0.4 eV from the valence band edge was measured for our best device. By comparing the combined defect density with that of a single amorphous layer the defect density at the interface is inferred to be 5x1012 cm -2. |
Keywords/Search Tags: | Amorphous, Heterojunctions, Defect density, Interface |
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