Epitaxial growth of Ag 2S films on MgO(001)

Abstract

Epitaxial films of monoclinic Ag 2S on polished and annealed surfaces and on cleaved surfaces of MgO(001) were prepared by molecular beam epitaxy. The films were characterized by X-ray diffraction method. Ag 2S films generally consisted of crystallites with orientations of (012), (−1,1,2) and (010) parallel to substrate surfaces, but for a thick film (180 nm) on cleaved MgO, the (010) orientation was not observed. In-plane orientation of the (−1,1,2) oriented crystallites was essentially the same as that of the (012) oriented crystallites in any case. That for the (010) oriented crystallites was not determined. For a film deposited on the polished MgO substrate, in-plane orientation for (012) oriented crystallites was [100]∥[110] MgO. For a film on the cleaved MgO substrate, the main in-plane orientation was [100]∥[100] MgO. For the thick film on the cleaved MgO substrate, the in-plane orientation was basically [4,−2,1]∥[100] MgO with slight modifications. There exist additional orientations due to twinning based on the monoclinic lattice of Ag 2S in each case.