Band offsets and trap-related electron transitions at interfaces of (100)InAs with atomic-layer deposited Al2O3

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Chou, Hsing-Yi
O'Connor, Éamon
O'Mahony, Aileen
Povey, Ian M.
Hurley, Paul K.
Dong, L.
Ye, P. D.
Afanas'ev, V. V.
Houssa, M.
Stesmans, A.
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Spectral analysis of optically excited currents in single-crystal (100)InAs/amorphous (a-)Al2O3/metal structures allows one to separate contributions stemming from the internal photoemission (IPE) of electrons into alumina and from the trapping-related displacement currents. IPE spectra suggest that the out-diffusion of In and, possibly, its incorporation in a-Al2O3 lead to the development of ≈0.4 eV wide conduction band (CB) tail states. The top of the InAs valence band is found at 3.45 ± 0.10 eV below the alumina CB bottom, i.e., at the same energy as at the GaAs/a-Al2O3 interface. This corresponds to the CB and the valence band offsets at the InAs/a-Al2O3 interface of 3.1 ± 0.1 eV and 2.5 ± 0.1 eV, respectively. However, atomic-layer deposition of alumina on InAs results in additional low-energy electron transitions with spectral thresholds in the range of 2.0–2.2 eV, which is close to the bandgap of AlAs. The latter suggests the interaction of As with Al, leading to an interlayer containing Al-As bonds providing a lower barrier for electron injection.
Alumina , Aluminium , Atomic layer deposition , Conduction bands , Electron traps , III-V semiconductors , Indium compounds , MOS capacitors , Photoelectron spectra , Photoelectron conversion , Valence bands
Chou, H.-Y., O'Connor, E., O'Mahony, A., Povey, I. M., Hurley, P. K., Dong, L., Ye, P. D., Afanas'ev, V. V., Houssa, M. and Stesmans, A. (2016) 'Band offsets and trap-related electron transitions at interfaces of (100)InAs with atomic-layer deposited Al2O3', Journal of Applied Physics, 120(23), pp. 235701. doi:10.1063/1.4971178
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© 2016, AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in J. Appl. Phys. 120, 235701 (2016) and may be found at