Schottky barrier of epitaxial (100)CoGa on GaAs

Schottky barrier heights in the epitaxial (100) CoGa/n-(100) GaAs diodes were studied by the I-V and internal photoemission methods. Diodes of these epitaxial contacts were shown to exhibit good rectifying behaviors and the forward current was found to follow the thermionic emission theory. Using the temperature dependence of the barrier heights, we show that the Schottky barrier heights are about 0.67 eV by I-V and 0.68 eV by internal photoemission measurements. The Schottky barrier height was found to be constant for contacting to n-type GaAs in the temperature range between 150 and 300 K. From this fact, we conclude that the metal Fermi level is pinned relatively to the GaAs conduction band minimum in this case. This finding is similar to other epitaxial contacting cases, CoSi₂/Si and ErSi₂/Si, where the Fermi level pins to the nearest semiconductor band [J. Y. Duboz, P. A. Badoz, F. Arnaud d'Avitaya, and E. Rosenche, Phys. Rev. B 40, 10 607 (1989)].