High quality 1 μm thick CdTe absorber layers grown by magnetron sputtering for solar cell application

Cadmium Telluride (CdTe) thin films with 1 μm thickness were grown by the magnetron sputtering on top of bare glass and glass/FTO/CdS stacks at different substrate temperatures. The crystallographic, morphological, optical and electrical properties of the as-deposited and CdCl2 immersed with subsequent thermally annealed (also known as CdCl2 treatment) films were studied through XRD, scanning electron microscopy (SEM), atomic force microscopy (AFM), UV–vis spectrometry and Hall Effect measurements, respectively. It has been revealed that the as-deposited films have poor crystallinity, while CdCl2 treatments improved crystallinity as well as surface morphology of the films. Increase of the grain size, surface roughness and absorption coefficients were observed in CdCl2 treated samples. The bulk carrier concentration also increased by a factor 10 in CdCl2 treated samples. The complete cell was also fabricated by sputtering technique with the configuration of glass/FTO/CdS/CdTe/CuxTe/Ni/Ag and the performance of the cell with and without CdCl2 treatment was evaluated under illumination of 1.5 AM. Vivid effects of CdCl2 treatment are also observed from the cell performances.

► CdTe thin films were synthesized for photovoltaic applications (i.e. absorber layer for CdTe thin film solar cells).
► Film quality was examined in terms of structural, optical and electrical upon the 1 micron growth of CdTe.
► Various growth parameters were optimized in CdTe sputtering deposition.
► The best CdTe film was subjected to the solar cell application and evaluation.