Characterisation of defects in p-GaN by admittance spectroscopy

ELSHERIF, O., VERNON-PARRY, Karen, EVANS-FREEMAN, J.H., AIREY, R.J., KAPPERS, M. and HUMPHREYS, C.J. (2011). Characterisation of defects in p-GaN by admittance spectroscopy. Physica B: Condensed Matter, 407 (15), 2960-2963.

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Link to published version:: 10.1016/j.physb.2011.08.077

Abstract

Mg-doped GaN films have been grown on (0 0 0 1) sapphire using metal organic vapour phase epitaxy. Use of different buffer layer strategies caused the threading dislocation density (TDD) in the GaN to be either approximately 2×109 cm−2 or 1×1010 cm−2. Frequency-dependent capacitance and conductance measurements at temperatures up to 450 K have been used to study the electronic states associated with the Mg doping, and to determine how these are affected by the TDD. Admittance spectroscopy of the films finds a single impurity-related acceptor level with an activation energy of 160±10 meV for [Mg] of about 1×1019 cm−3, and 120±10 eV as the Mg precursor flux decreased. This level is thought to be associated with the Mg acceptor state. The TDD has no discernible effect on the trap detected by admittance spectroscopy. We compare these results with cathodoluminescence measurements reported in the literature, which reveal that most threading dislocations are non-radiative recombination centres, and discuss possible reasons why our admittance spectroscopy have not detected electrically active defects associated with threading dislocations.

Item Type: Article
Research Institute, Centre or Group: Materials and Engineering Research Institute > Thin Films Research Centre > Electronic Materials and Sensors Research Group
Identification Number: 10.1016/j.physb.2011.08.077
Depositing User: Helen Garner
Date Deposited: 24 Oct 2011 14:39
Last Modified: 21 Sep 2012 14:20
URI: http://shura.shu.ac.uk/id/eprint/3970

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