Characterization of space charge layer deep defects in n~+-CdS/p-CdTe solar cells by temperature dependent capacitance spectroscopy

摘要

Temperature Dependent Capacitance Spectroscopy (TDCS) was used to identify carrier trapping defects in thin film n~+-CdS/p-CdTe solar cells, made with evaporated Cu as a primary back contact. By investigating the reverse bias junction capacitance, TDCS allows to identify the energy levels of depletion layer defects. The trap energy levels and trap concentrations were derived from temperature-dependent capacitance spectra. Three distinct deep level traps were observed from the high-temperature (T > 300 K) TDCS due to the ionization of impurity centers located in the depletion region of n~+-CdS/p-CdTe junction. The observed levels were also reported by other characterization techniques. TDCS seems to be a much simpler characterization technique for accurate evaluation of deep defects in n~+-CdS/p-CdTe solar cells.