Growth and characterization of Cd<inf>1&#x2212;x</inf>Mg<inf>x</inf>Te thin films for possible application in high-efficiency solar cells

Abstract

Expanded band gap ternary alloys, such as Cd 1-x Mg x Te, could be beneficial for formation of high-efficiency CdTe solar cells structures, such as multi-junction and electron reflector devices. Cd 1-x Mg x Te thin films were grown by sideby-side co-evaporation from CdTe and Mg precursors. Optical measurements reveal increased band gap with higher Mg incorporation and lateral band gap grading across the substrate. SEM imaging denotes a grain size decrease with Mg incorporation. XPS analysis indicates Mg directly replaces Cd in the film. TEC10/CdS/Cd 1-x Mg x Te structures with and without CdCl 2 treatment demonstrate photovoltaic diode behavior similar to typical CdS/CdTe devices. LBIC and QE measurements register grading consistent with band gap grading of the film. Although successful, refinement of Cd 1-x Mg x Te thin film co-evaporation is needed to improve spatial uniformity for large area deposition.

Progress towards a CdS/CdTe solar cell implementing An Electron Reflector

“…Deposition of Cd 1-x Mg x Te thin films were performed in the previously described Deposition Research Chamber (DRC) [5] using a co-sublimation process suitable for large areas [6]. The co-sublimation process uses a sublimation vapor source with an added vapor Mg to alloy the film during growth.…”

“…In our previous work we demonstrated the formation of Cd 1-x Mg x Te thin films by side-by-side sublimation [5] and more recently by a co-sublimation method suitable for scaling to larger areas [6]. In this work, we present an overview of our progress towards implementing the Cd 1-x Mg x Te as the ER layer in CdS/CdTe cells.…”