Transport Properties of CuInTe2 Thin Films Obtained by the Electrochemical Route

CuInTe2 (CIT) thin films were potentiostatically electrodeposited onto cadmium sulfide thin films coated on fluorine doped tin oxide (FTO) glass in an aqueous bath at 75 degrees C by the standard three-electrode system at -0.7 V and -0.8 V, with respect to an Ag/AgCl reference electrode. The electrodeposited layers were heat treated at similar to 80 degrees C in air ambient for 60 min. X-ray diffraction pattern and Raman analysis confirmed the formation of chalcopyrite CIT thin films upon heat treatment. The optical band gap of heat treated CIT films was found to be similar to 1.0 eV and 0.95 eV deposited at -0.7 V and -0.8 V, respectively. Compact and good adhesive growth of CIT layers onto CdS coated FTO substrates is confirmed by field emission scanning electron microscopy. The current density-voltage (J-V) and capacitance-voltage (C-V) measurement was studied to understand the electronic quality of material for development of CIT layers for solar cell applications. The current density was found to be increased by two orders of magnitude upon low-temperature heat treatment. The capacitance-voltage measurement showed sharp depletion and accumulation region. The built in potential was found to be similar to 60 mV and 145 mV in the as-deposited samples, deposited at -0.7 V and -0.8 V, respectively, whereas upon heat treatment it shifted to 159 mV and 210 mV. The capacitance of the CIT films was found to be a function of applied bias and increased with increasing the bias voltage. The depletion width of the heat treated sample was found to be similar to 20 nm and 200 nm for the sample deposited at -0.7 V and -0.8 V, respectively. Thus, the sample deposited at -0.8 V shows optimum electronic properties and is found to be suitable for opto-electronic applications.