Thin Films of Cadmium Telluride Produced Using Stacked Elemental Layer (Sel) Processing for Use in Thin Film Solar Cells†

Abstract

The stacked elemental layer (SEL) technique has been used to synthesise thin films of CdTe. This technique consists of depositing alternate layers of Cd/Te in the stoichiometric ratio and then annealing the stack to react the layers to form the compound. The Cd and T e layers were deposited using thermal evaporation and annealed in nitrogen, vacuum or air. Transmittance and reflectance data, X-ray diffraction data and scanning electron microscopy observations of the surface topology are given for the layers produced. Post synthesis annealing of the layers using CuCI,/CdCl,/methanol was also investigated. This was found to substantially increase the grain size of the layers produced. This process promises to be a low cost method for producing large areas suitable for luse in solar cell structures. A preliminary energy analysis has been carried out and energy payback times and energy ratios are presented.

The formation of CdTe thin films by the stacked elemental layer method

“…The bandgap energy is obtained by intercepting the linear portion of the absorption curves to the energy axis. The value 1.5 eV does not depend upon annealing temperature and is in good agreement with literature [5,6]. The tendency of the absorption edge to become more abrupt at higher annealing temperatures is certainly related to the observed improvement in the crystallinity of these films.…”

“…This work investigates the physical properties of CdTe films prepared by a more recent deposition method: the Stacked Elemental Layer (SEL) technique. This process was originally developed to produce copper indium diselenide thin films [4] but has also been used to produce CdTe films [5,6]. It consists of sequentially depositing Te and Cd layers and then annealing the resulting stack in order to form the compound.…”

Studies on morphological change and optical properties for various Zn concentrations in CdTe thin film prepared by stacked elemental layer method

“…SEL technique was originally developed to produce CuInSe 2 thin films [19]. It has also been used to produce CdTe films [20]. Cruz et al have reported the influence of post deposition treatment on CdTe prepared by SEL method.…”

Optimization of Thickness and Number of Layers for CdTe Films Deposited by Stacked Elemental Layers Method and Annealed in Different Environments

“…The SEL is a suitable technique for large area development, simplicity, controlling deposition parameters, and the flexibility in the choice of preparation method of the elemental stacks [10][11][12][13].…”