Photoconductive properties of hot wall deposited CdSe0.6Te0.4 thin films

CdSe0.6Te0.4 compound has been prepared using high purity elemental cadmium, tellurium and selenium. Thin films of CdSe0.6Te0.4 have been deposited on glass substrates by hot wall deposition technique. The main feature of the hot wall system is the heated linear quartz tube, which serves to enclose and direct the vapor from source to substrate. The hot wall setup used in the present study consists of a quartz tube of 6.5 cm length and 1 cm diameter with one end open and the other end closed. Kanthal wire wound closely along the length of the quartz tube heats the wall of the quartz tube. Independent heater coils are used to heat the source and wall of the tube. The composition of the films has been determined using energy dispersive X-ray analysis. The transmittance spectra of the deposited films show that the CdSe0.6Te0.4 films exhibit fairly good transparency above 800 nm. The photoconductive properties of the films have been studied as a function of light intensity and wavelength. From the spectral response characteristics of photocurrent the band gap of the CdSe0.6Te0.4 films has been determined and is found to be 1.46 eV. The variation of photosensitivity with light intensity has been studied.