Exploration of copper-free ZnTe buffer layers for CdTe-based solar cells

Development of copper-free ZnTe buffer layers for CdTe-based solar cells is an important avenue for improving stability. Group V elements offer a path towards that goal. This work explores two group V elements, phosphorous and antimony, as candidates for making copper-free p-type ZnTe buffer layer using thermal evaporation. It is found that incorporation of both elements into ZnTe film can easily be done. In addition, as deposited ZnTe films are Te-rich and Cd1-x Znx Te alloys form upon co-evaporation of ZnTe and Cd3P2, improving crystallinity and stoichiometry of the film. Activation of P poses a challenge, while ZnTe films with Sb produced good sheet resistance values.