Fermi-level pinning and intrinsic surface states of Al$_{1−x}$In$_{x}$N(101¯0) surfaces

Portz, V.; Neugebauer, J.; Carlin, J.-F.; Schnedler, M.; Grandjean, N.; Ebert, Ph.; Dunin-Borkowski, Rafal; Eisele, H.; Butté, R.; Lymperakis, L.

doi:10.1063/1.4973765

Journal Article

FZJ-2017-01023

Fermi-level pinning and intrinsic surface states of Al$_{1−x}$In$_{x}$N(101¯0) surfaces

Portz, V.FZJ* ; Schnedler, M.FZJ* ; Lymperakis, L. ; Neugebauer, J. ; Eisele, H. ; Carlin, J.-F. ; Butté, R. ; Grandjean, N. ; Dunin-Borkowski, R.FZJ* ; Ebert, P.FZJ*

2017
American Inst. of Physics Melville, NY

Applied physics letters 110(2), 022104 - (2017) [10.1063/1.4973765]

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Please use a persistent id in citations: http://hdl.handle.net/2128/16968 doi:10.1063/1.4973765

Abstract: The electronic structure of Al1−xInxN(101⎯⎯0) surfaces is investigated by cross-sectional scanning tunneling spectroscopy and density functional theory calculations. The surface exhibits empty Al and/or In-derived dangling bond states, which are calculated to be within the fundamental bulk band gap for In compositions smaller than 60%. The energy of the lowest empty In-derived surface state is extracted from the tunnel spectra for lattice-matched Al1–xInxN with In compositions of x = 0.19 and x = 0.20 to be EC − 1.82 ± 0.41 and EC − 1.80 ± 0.56 eV, respectively, in good agreement with the calculated energies. Under growth conditions, the Fermi level is hence pinned (unpinned) for In compositions smaller (larger) than 60%. The analysis of the tunnel spectra suggests an electron affinity of ∼3.5 eV for nonpolar lattice-matched Al1–xInxN cleavage surfaces, which is large compared to linearly interpolated values of polar AlN and InN (0001) surfaces.

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