Structural properties of MBE grown Cu(In, Ga)S2 layers on Si

The epitaxial growth of the quaternary CuIn(1-x)GaxS2 system with 0 less than or equal to x less than or equal to 1 on silicon substrates is investigated. Using molecular beam epitaxy, the layers were deposited on sulphur-terminated Si at a substrate temperature of typically 820 K. Reflection high-energy electron diffraction, Rutherford backscattering, X-ray diffraction, and transmission electron microscopy are employed to gain insight into the structural properties of the epitaxial layers with an emphasis on the interplay of lattice mismatch and cation sublattice ordering. All compounds grow epitaxially on Si(111). The quaternary films show a coexistence of chalcopyrite and metastable CuAu-type cation ordering. Lattice match to Si is found for gallium atomic fractions of x=0.41(2). 11 refs.