Using hybrid quantum mechanical/molecular mechanical (QM/MM) embedded cluster calculations, we investigate the stabilization of silicon and oxygen dopants in GaN. Formation energies of Si on a Ga site and O on an N site are calculated at two levels of theory using conventional thermochemical and kinetic exchange and correlation density functionals (B97-2 and BB1k). We confirm the shallow donor nature of these substitutional defects. We find that the 0/1+ transition levels for both Si and O species lie well above the bottom of the conduction band, in agreement with previous supercell-based simulations. The origin of this artifact is discussed in the context of relevant experimental results and we show how correct in-gap shallow levels can be ascertained in good agreement with experiment.
|Physica Status Solidi (A) Applications and Materials Science
|Published - 1 Apr 2017
Bibliographical noteFunding Information:
Zijuan Xie thanks the China Scholarship Council (CSC) for support. We are grateful to Alex Ganose and Stephen Shevlin for technical help and Audrius Alkauskas for useful discussion. The EPSRC is acknowledged for funding (EP/K038419, EP/I03014X, EP/K016288). Computational resources were provided though the Materials Chemistry Consortium supported by EPSRC grant EP/L000202.
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- cluster calculations
- n-type semiconductors