title: Electron and hole stability in GaN and ZnO.
abstract: We assess the thermodynamic doping limits of GaN and ZnO on the basis of point defect calculations performed using the embedded cluster approach and employing a hybrid non-local density functional for the quantum mechanical region. Within this approach we have calculated a staggered (type-II) valence band alignment between the two materials, with the N 2p states contributing to the lower ionization potential of GaN. With respect to the stability of free electron and hole carriers, redox reactions resulting in charge compensation by ionic defects are found to be largely endothermic (unfavourable) for electrons and exothermic (favourable) for holes, which is consistent with the efficacy of electron conduction in these materials. Approaches for overcoming these fundamental thermodynamic limits are discussed.
authors.affiliation: Kathleen Lonsdale Materials Chemistry, Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK. a.walsh@bath.ac.uk
authors.forename: Aron
authors.initials: A
authors.lastname: Walsh
authors.forename: C Richard A
authors.initials: CR
authors.lastname: Catlow
authors.forename: Martina
authors.initials: M
authors.lastname: Miskufova
authors.forename: Alexey A
authors.initials: AA
authors.lastname: Sokol
mesh_terms: D004583:Electrons; D005708:Gallium / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011789:Quantum Theory; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D014867:Water; D005708:Gallium; D015034:Zinc Oxide; C027235:gallium nitrate