Effect of pulse reversal on the properties of pulse plated CdSe _x Te_1−x thin films

Abstract

CdSe _x Te_1−x thin films with 0 < x < 1 were deposited on titanium and conducting glass substrates by pulse electrodeposition using microprocessor control. Formation of the solid solution takes place for values of x(0 < x < 1). The films were characterized by X-ray diffraction. While the as-deposited films are cubic in nature, those annealed at 475 °C in air indicate hexagonal structure and the lattice parameters increase with increasing value of x. From the optical absorption measurements the band gap of the material was calculated. The value of the band gap varies from 1.42 to 1.70 eV as x varies from 0 to 1. The photoelectrochemical (PEC) characteristics were obtained for all compositions of CdSe _x Te_1−x (x = 0–1). The output parameters for CdSe_0.66Te_0.34 with 9% duty cycle at an intensity of 80 mW cm⁻² using 1 M polysulphide as the redox electrolyte, are V _OC of 398 mV, J _SC of 5.59 mA cm⁻², ff of 0.45, η of 4.73%, R _s of 13 Ω, R _sh of 1.50 kΩ. The output parameters were found to increase with 60 ms pulse reversal. After photoetching for 40 s, a V _OC of 481 mV, J _SC of 16.00 mA cm⁻², ff of 0.57, η of 5.46%, R _s of 6 Ω, R _sh of 2.16 kΩ were obtained.