Epitaxial CoGa and textured CoAs contacts on Ga1−xAlxAs fabricated by molecular-beam epitaxy

Abstract

Films of CoGa and CoAs have been deposited on Ga_1−xAl_xAs surfaces. Control of the Ga_1−xAl_xAs surface prior to CoGa deposition results in the preferential formation of two epitaxial orientations, either (100)[011]CoGa∥(100)[011]Ga_1−xAl_xAs or (110)[001]CoGa∥(100)[01̄1̄]Ga_1−xAl_xAs. The crystalline quality of (100)‐oriented CoGa was good as determined by Rutherford backscattering with channeling measurements, χ_min∼7%, and cross‐sectional transmission electron microscopy. The (110)CoGa films did not have as good a crystalline quality, χ_min∼41%. CoAs films were found to be highly textured, but not single crystal. Schottky barrier diodes fabricated from CoGa/Ga_1−xAl_xAs and CoAs/Ga_1−xAl_xAs showed good characteristics with low ideality factors, n<1.15. In general CoGa contacts had a ∼0.1 eV lower barrier height than CoAs.