Abstract
Data are presented here that show the effects of temperature on the kinetics of metastable defect formation in undoped a-Si:H over the range 45°-110°C. CPM (Constant Photocurrent Method), photoconductivity, and dark conductivity measurements were made and provide independent checks of the defect generation behavior. A stretched exponential description of defect formation as a function of time was used to fit the CPM defect density data. The stretched exponential time constant, τSE, is thermally activated with an apparent activation energy of 1 eV, a value that agrees well with data for defect anneal and solar cell degradation. The data indicate that thermal terms are not negligible for temperatures as low as 45°C, and therefore should be included in any model of the kinetics of defect formation. The role of adistribution of anneal energies and the regimes of dominance of thermal and optical rate terms are discussed in the context of the model.
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Acknowledgement
This work was supported by the Electric Power Research Institute and benefited from facilities made available to Stanford University by the National Science Foundation through the Center for Materials Research at Stanford University. We also gratefully acknowledge provision of samples by Murray Bennett and Liyou Yang at Solarex, Inc.
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Benatar, L., Grimbergen, M., Fahrenbruch, A. et al. Isolation of Temperature Effects on the Kinetics of Light Induced Defect Generation in a-Si:H. MRS Online Proceedings Library 258, 461–466 (1992). https://doi.org/10.1557/PROC-258-461
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DOI: https://doi.org/10.1557/PROC-258-461