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Mechanism for dicarbon defect formation in AlAs and GaAs

Latham, CD, Jones, R, Haugk, M, Frauenheim, T and Briddon, PR (1999) Mechanism for dicarbon defect formation in AlAs and GaAs Physica B: Condensed Matter, 273–27. pp. 784-787.

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There is a need to understand the degradation mechanism which results in the loss of substitutional CAs shallow acceptors in AlAs and GaAs containing high concentrations (≳1020 cm−1) of carbon. The activation energy for the migration of interstitial carbon atoms, Ci, in AlAs and GaAs is calculated using a local-density functional-based method, AIMPRO, to be ≲1 eV. This model is consistent with a ‘kick-out’ mechanism being responsible for the observed loss of CAs, and formation of dicarbon defects. Three local minima separated by only a few tenths of an eV are encountered by a diffusing carbon atom along its path through the crystal. These have (C–As)As split interstitial, bond-centred M–C–As, and (C–M)M split interstitial structures (M=Al, Ga). Interstitial dicarbon defects, (C–C)i, or substitutional dicarbon defects, (C–C)As, are produced depending on whether a Ci meets a (C–M)M split interstitial or a CAs. These possess Raman-active C–C vibrational modes near to that for a free dicarbon molecule, C2.

Item Type: Article
Divisions : Surrey research (other units)
Authors :
Jones, R
Haugk, M
Frauenheim, T
Briddon, PR
Date : 15 December 1999
DOI : 10.1016/S0921-4526(99)00649-3
Depositing User : Symplectic Elements
Date Deposited : 17 May 2017 12:37
Last Modified : 24 Jan 2020 22:33

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