Annealing Effect on BaCuSe Thin Films

The Barium Copper Selenide films (BaCuSe) growth by a chemical bath technique method. The annealing effect on morphology and optical properties were studied. The as-deposited and annealed films have grains size (400 μm -1mm). The different in grains size from each other indicate irregular growth rate of the grains. The BaCuSe films are Ultraviolet (UV) absorbers and Visible – Near Infrared (Vis – NIR) transmitter’s material. Thus defines transparency range of as-deposited and annealed BaCuSe films for covering whole visible and near infrared spectrum of electromagnetic radiation. The direct bandgap energy for as-deposited and annealed film at 150°C and 200°C are 2.66 eV, 2.93 eV, and 3.18 eV respectively while as-deposited and annealed have the same indirect bandgap of 0.95 eV. Moreover, annealed BaCuSe films have largest velocity of propagation compared to the as-deposited BaCuSe film. However, as-deposited BaCuSe film has largest dispersion in the ultraviolet (UV) spectrum of electromagnetic radiation compared to the annealed BaCuSe films. The as-deposited BaCuSe film has largest extinction coefficient compared to the annealed BaCuSe films. The as-deposited BaCuSe film has largest real and imaginary dielectric functions compared to the annealed BaCuSe films. The real and imaginary part of optical conductivity of BaCuSe films for both as-deposited and annealed increases with increasing frequency. The dissipation factor shows that incident photon energy loss in form of heat to surrounding is very low. All these desirable properties made the material to be a good candidate for application in tandem configuration photovoltaic cell.