Crystallographic Characterization of AgGaTe2, AgAlTe2, and Ag(Ga,Al)Te2 Grown by Closed-Space Sublimation

AgGaTe 2 , AgAlTe 2 , and Ag(Ga,Al)Te 2 layers were grown by the closed-space sublimation method on c -plane sapphire substrates. The crystallographic properties of the AgGaTe 2 and AgAlTe 2 layers were then analyzed by x-ray diffraction (XRD). Very strong 112 diffraction peaks were observed in the XRD spectra of both layers, and it was clear the (112) orientation was predominant in both layers. The orientation and domain structure of the AgAlTe 2 layer were carefully analyzed by XRD pole-figure measurement, and the effect of substrate surface atomic arrangement on the crystallinity of the AgAlTe 2 layer was investigated. On the basis of the pole-figure image, six types of {112} domain were confirmed in the layer, and [ 1 ¯ 10] in one domain was regarded as aligned with the sapphire’s a -axis when the layer was formed on the c -plane sapphire substrate surface. In addition to crystallographic characterization, the optical properties of the Ag(Ga,Al)Te 2 layer were evaluated on the basis of transmittance measurements. The optical bandgap, derived from the transmittance spectrum, was approximately 2.0 eV. This value was between the bandgap values of AgGaTe 2 and AgAlTe 2 . These results showed that an alloy of AgGaTe 2 and AgAlTe 2 had been grown successfully.