UV-induced formation of oxygen-derived dangling bonds on hydroxyl-terminated SiC. (9th October 2018)

• Record Type: Journal Article
• Authors: Aghdassi, Nabi; Krüger, Peter; Linden, Steffen; Dulson, Dorothea; Zacharias, Helmut
• Is Part Of: Journal of physics. Volume 30:Number 43(2018)
• Publication Date: 2018-10-09
• Subjects: silicon carbide -- hydroxyl termination -- surface dangling bonds -- electronic surface band structure -- photoelectron spectroscopy -- self-interaction-corrected pseudopotentials; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aae2cc
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: A combined theoretical and multi-technique experimental study was employed to comprehensively determine the electronic structure of 6H–SiC(0 0 0 1) surfaces upon hydroxyl and oxygen termination. We demonstrate the UV-induced formation of single-coordinated oxygen radicals in on-top sites above the atoms of the uppermost silicon layer of the substrate on initially hydroxyl-terminated SiC. Such a configuration of oxygen radicals represents an unprecedented adsorbate-derived system of unpaired electrons, bearing analogy to silicon and carbon dangling bonds on clean, unreconstructed SiC surfaces. We evidence the presence of adsorbate-derived surface states within the fundamental band gap for both hydroxyl- and oxygen-terminated SiC. For hydroxyl termination, a hydrogen-induced unoccupied surface state is revealed consistently by inverse photoemission spectroscopy and density-functional theory calculations employing self-interaction-corrected pseudopotentials (DFT-SIC). The formation of oxygen dangling bonds is accompanied by the occurrence of an occupied surface state derived from p x - and p y -orbitals associated with the unpaired electrons as proven by both ultraviolet photoemission spectroscopy and DFT-SIC.