COMPARISON OF TRAP STATES BETWEEN CIGSS/CdS/ZnO AND Cd PE CIGSS/ZnO CELLS

In the continuing attempt to find an alternative to CdS windows for CIS absorbers, recent results show that a Cd-doped CIGS surface can produce a cell comparable to the best CdS/CIGS cells. We extend this work to include CIGSSbased cells utilizing the same absorber preparation process as is currently used to manufacture commercial photovoltaic modules. We use current-voltage, quantum efficiency, capacitance-frequency-temperature, and capacitance-voltage temperature measurements to extract parameters and qualitative information pertaining to current transport in CIGSS-based cells. These cells have p-n junctions formed by either chemical-bath deposition of CdS or Cd-doping of the CIGSS using a partial electrolyte of Cd. In addition, we use the AMPS modeling software to investigate mechanisms of Cd-doping.