The Nature of Native and Light Induced Defect States in i-layers of High Quality a-Si:H Solar Cells Derived from Dark Forward-Bias Current-Voltage Characteristics

Results are presented on the defect state distributions in intrinsic a-Si:H layers with and without hydrogen dilution in p-i-n solar cells obtained directly from the analysis of dark forward-bias current-voltage (JD-V) characteristics. It is shown that there are distinct differences in the distributions of both native and light induced defect states between the two types of i-layers. Computer simulations using these distributions are presented which show excellent agreement with the experimental results not only for the JD-V but more importantly for the bias dependent differential diode quality factor n(V) characteristics. Results are also presented on the nature of the gap states and their evolution with light induced degradation as well as their effects on the performance and stability of high quality a-Si:H solar cells.