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 CuCl/GaP 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 °C is abrupt, but undergoes a massive chemical reaction which leads to the formation of a copper phosphide layer at high temperature (≥300 °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 (1×1) 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.