Study of Ho doped (Cd-Ag)S thin films prepared by CBD method

Ho doped (Cd-Ag)S semiconducting thin films have been grown on the glass substrate by chemical bath deposition method at room temperature. The semiconducting films were grown in bath containing aqueous solution of silver nitrate, cadmium acetrate, thiourea, Ethylenediaminetetraacetic (EDTA), triethanolamine (TEA), ammonia and holmium nitrate. Silver nitrate is used as the silver (Ag) ion source, cadmium acetate as the cadmium (Cd) ion source, thiourea for sulphur ion source; EDTA and TEA are the complexing agents while ammonia is used for maintaing pH. Ho(NO3)(3) is taken for the Ho ion. The absorption spectra of the prepared thin films fall in the UV region. Absorption edge of spectra shifted toward lower wavelength side as compared to the undoped films of (Cd-Ag)S and the increase in Ho volume in the prepared sample further shifted the edge towards lower wavelength. Band gaps calculated from tauc's plot also showed increase in values for doped samples. Increase in band gap is indicated of reduced particle size of the prepared Ho doped films. The Photoluminescence emission peaks of all the prepared films around 575-600 nm wavelength and excitation peaks are found at 260-276 nm. The SEM studies of Ho doped (Cd-Ag)S films show the globular ball type particles grouped together and also flakes type structure observed in 8 ml Ho doped films. Particle size estimated from micrograhs are ranging from 60 to 180 nm.