Defect Density in Doped Amorphous Layer and Interface of Silicon Heterojunction Devices Obtained with the Constant Photocurrent Method

We present here the application of CPM for the examination of defect density in the doped amorphous silicon layer and the amorphous-crystalline silicon interface of silicon heterojunction photovoltaic devices. CPM derived absorption and internal quantum efficiency (QE) spectra of the devices are measured. A simple model is proposed wherein the amorphous layer and the interface constitute one absorbing layer while the crystalline substrate forms the other absorbing layer. On the basis of this model, we obtain the combined defect density in the amorphous film and interface. Also, an estimate of the defect density at the interface is inferred using an independent measure of the defect density in a similar amorphous film