Peter Lechner

Sub-bandgap absorption in a-Si:H pin cells illuminated with infrared light

We discuss some aspects of the Constant Photocurrent Method (CPM) when applied to a-Si:H pin diodes. One can get valuable information on midgap defect states when the cell is reverse biased. A direct correlation is established between a device characterizing quantity, the fill factor (FF), and the concentration of defects which is related to the sub-bandgap optical absorption constant (αD). Thus changes in the i-layer of pin cells, due to the creation of metastable defects by light-soaking or forward-current injection, are observed in changes of both αD and FF.