Treatment effects on deep levels in CdTe based solar cells

This paper presents capacitance-voltage, admittance spectroscopy, and drive-level capacitance profiling (DLCP) data on CdTe solar cells prepared with and without standard treatments (CdCl₂ treatment and/or BrMeOH etch). The DLCP technique confirmed previous results and added the ability to measure deep trapping state spatial distributions. The concentrations and depth profiles of the deep states observed depended upon the treatments used. High concentrations (>1×10¹⁵ cm^-3) of trapping states with a variety of characteristic frequencies exist in all cells studied. The sample with neither standard treatment had the lowest concentration of deep trapping states.