Growth of AgGaTe2 and AgAlTe2 Layers for Novel Photovoltaic Materials

AgGaTe₂ and AgAlTe₂ layers were grown on a-plane sapphire substrates by closed-space sublimation. These compounds replace Cd in CdTe with group I and III elements, and are, hence, expected to be ideal novel candidate materials for solar cells. The grown layers were confirmed to be stoichiometric AgGaTe₂ and AgAlTe₂ by x-ray diffraction (XRD). The AgAlTe₂ layers had strong preference for the (112) orientation. The XRD spectrum of the AgGaTe₂ layer was different from that of the AgAlTe₂ layer, and strong peaks were observed for (103) and (110) diffraction. The variation in orientations of the grown layers was analyzed in detail by use of XRD pole figures, which revealed that the AgGaTe₂ layers had an epitaxial relationship with the a-plane sapphire substrates.