INTERFACE STOICHIOMETRY DEPENDENCE OF THE SCHOTTKY-BARRIER HEIGHT OF COGA AND GAAS

The Schottky barrier formation of CoGa on (100)n-GaAs is investigated. CoGa is grown by molecular-beam epitaxy, and the epitaxial orientation is controlled by the initial growth conditions of the GaAs substrate. Schottky diodes with three different phases of CoGa: (100)CoGa, (110)CoGa and mix of (100) and (110)CoGa, are fabricated and Schottky barrier heights are measured by I-V, C-V, and internal photoemission. All these three types of diodes have different values of barrier height, indicating that the mechanisms of the barrier formation for these three phases are different. The plausible mechanisms for the change of the Fermi level pinning position of these phases are discussed. Finally, the temperature dependence of the Schottky barrier height is also examined and the barrier height is found to be constant from 150 to 300 K for all of the phases.