Electronic properties of cesium on 6H-SiC surfaces

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Abstract
The adsorption of cesium on clean {0001} surfaces of n‐ and p‐6H‐SiC samples at low temperatures was investigated by using Auger electron, x‐ray photoelectron, and ultraviolet photoelectron spectroscopy as well as a Kelvin probe. At clean surfaces the Fermi level is pinned at 1.2 eV above the valence‐band maximum and the ionization energy measures 5.7 and 5.8 eV on Siand become metallic after the deposition of the first Cs layer. For submonolayer coverages, Cs‐induced surface donors form at 2.96 eV above the valence‐band maximum. They are due to covalent Cs–Si bonds. The barrier height of Cs/6H‐SiC Schottky contacts was found as 0.57±0.05 eV with n‐type and 2.28±0.1 eV with p‐type doped samples. These results confirm the concept that the continuum of metal‐induced gap states determines the barrier heights of ideal metal‐semiconductor contacts.