Interfacial optical spectra in amorphous silicon based pin solar cells

We present infrared transmittance and reflection modulation spectra for changes in the reverse bias voltage across a variety of amorphous silicon (a-Si:H) based pin and min solar cells and diodes. The spectra originate with the change in charge state of levels near the two intrinsic-layer interfaces. The spectra vary significantly for differing interfaces, and we therefore propose their application to ex situ monitoring of the interfaces in solar cell manufacturing. The measurements also support the model that phosphorus doping occurs through dopant complex formation at the concentrations commonly used for solar cell fabrication.