Opto-electrical Investigation of Thallium Cuprate (Tl2Cu) Binary Chalcogenide Thin Films via Chemical Bath Deposition Technique

Abstract

Thallium Cuprate (Tl2Cu) thin films were grown on microscope glass slide in order to investigate its opto-electrical properties and examine the effects of annealing on the deposited films and suitability for solar applications. Thallium was chosen to serve as alternative and relief stress on the availability of germanium. Chemical bath deposition (CBD) technique was used and the chemical bath was developed from aqueous solution of Thallium Chloride (TlCl2) and copper(II)chloride dihydrate (CuCl2.2H2O) as precursors with trisodiumcitrate (TSC) and triethanolamine (TEA) as the complexing agents. The bath was conditioned at 80ºC for about 5 hours to deposit the films. A four-point probe machine and an Avantes Electrophotometer operating in the 200-1000 nm wavelength range were used to characterize the deposited thin films. The optical properties such as reflectance, transmittance, absorbance and bandgap energy and the electrical properties of the grown films were reported in this article. This study revealed that annealing temperature has a linear proportion effect on the reflectance of Tl2Cu deposited. The absorption spectra exhibited a relatively high direct bandgap. Materials of this nature are good for window layers where the film is not to capture any photon but serve as passage to the absorber layer where charge carriers are produced.