title: Tuning the surface charge properties of epitaxial InN nanowires.
abstract: We have investigated the correlated surface electronic and optical properties of [0001]-oriented epitaxial InN nanowires grown directly on silicon. By dramatically improving the epitaxial growth process, we have achieved, for the first time, intrinsic InN both within the bulk and at nonpolar InN surfaces. The near-surface Fermi-level was measured to be ∼0.55 eV above the valence band maximum for undoped InN nanowires, suggesting the absence of surface electron accumulation and Fermi-level pinning. This result is in direct contrast to the problematic degenerate two-dimensional electron gas universally observed on grown surfaces of n-type degenerate InN. We have further demonstrated that the surface charge properties of InN nanowires, including the formation of two-dimensional electron gas and the optical emission characteristics can be precisely tuned through controlled n-type doping. At relatively high doping levels in this study, the near-surface Fermi-level was found to be pinned at ∼0.95-1.3 eV above the valence band maximum. Through these trends, well captured by the effective mass and ab initio materials modeling, we have unambiguously identified the definitive role of surface doping in tuning the surface charge properties of InN.
authors.affiliation: Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, QC, H3A 2A7, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Zhao
authors.forename: S
authors.initials: S
authors.lastname: Fathololoumi
authors.forename: K H
authors.initials: KH
authors.lastname: Bevan
authors.forename: D P
authors.initials: DP
authors.lastname: Liu
authors.forename: M G
authors.initials: MG
authors.lastname: Kibria
authors.forename: Q
authors.initials: Q
authors.lastname: Li
authors.forename: G T
authors.initials: GT
authors.lastname: Wang
authors.forename: Hong
authors.initials: H
authors.lastname: Guo
authors.forename: Z
authors.initials: Z
authors.lastname: Mi
mesh_terms: D003460:Crystallization / Q000379:methods*; D007204:Indium / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D007204:Indium; C513701:indium nitride