Scanning tunnelling spectroscopy of quantized electron accumulation at in <inf>x</inf>Ga <inf>1-x</inf>N surfaces

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Journal Article
Physica Status Solidi (A) Applications and Materials Science, 2006, 203 (1), pp. 85 - 92
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Electron tunnelling spectroscopy has been used to investigate quantized levels in electron accumulation layers at InGaN surfaces. The tunnelling spectra exhibit a plateau in the normalized conductance which widens with increasing Ga-content, corresponding to the band gap of InGaN. The measured In xGa 1-xN band gaps (between ∼0.65 eV for x = 1 and 1.8 eV for x - 0.43) are consistent with the band gaps determined by previous optical absorption and cathodoluminescence spectroscopy. Additional structures in the spectra reflect the two-dimensional electronic subbands in the surface quantum well. The subband energies depend on Ga-content, bulk doping level and the resultant shape of the surface potential well. The tunnelling spectra are compared with calculations of the potential well, the charge-profile and the subband energies. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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