EPITAXIAL-GROWTH AND CHARACTERIZATION OF CUCL(110)/GAP(110)

Epitaxial layers of the ionic zinc blende compound CuCl are grown on the (110) surface of GaP. The growth is performed by congruent evaporation from a single CuCl source. Surface and interface properties of CuCVGaP are studied with Auger electron spectroscopy, ultraviolet and x-ray photoemission spectroscopy, electron energy-loss spectroscopy, and low-energy electron diffraction. The interface formed at 100-degrees-C is abrupt, but undergoes a massive chemical reaction which leads to the formation of a copper phosphide layer at high temperature (greater-than-or-equal-to 300-degrees-C). The valence band discontinuity is 0.85 eV +/- 0.15 at the abrupt CuCl/GaP interface. The CuCl(110) surface is atomically ordered and exhibits a (1 X 1) unit cell. Its atomic geometry is determined by multiple scattering analysis of low-energy electron diffraction intensities. The surface is found to be relaxed in a way which is entirely compatible with the "universal" structure of cleavage surfaces of tetrahedrally coordinated III-V and II-VI compound semiconductors.