Band-gap bowing and p-type doping of (Zn,Mg, Be)O wide-gap
semiconductor alloys: a first-principles study |
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Authors: | H-L Shi Y Duan |
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Institution: | (1) State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing, 100083, P.R. China;(2) Department of Physics, School of Sciences, China University of Mining and Technology, Xuzhou, 221008, P.R. China |
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Abstract: | Using a first-principles band-structure method and a
special quasirandom structure (SQS) approach, we systematically
calculate the band gap bowing parameters and p-type doping
properties of (Zn, Mg, Be)O related random ternary and quaternary
alloys. We show that the bowing parameters for ZnBeO and MgBeO
alloys are large and dependent on composition. This is due to the
size difference and chemical mismatch between Be and Zn(Mg) atoms.
We also demonstrate that adding a small amount of Be into MgO
reduces the band gap indicating that the bowing parameter is
larger than the band-gap difference. We select an ideal N atom
with lower p atomic energy level as dopant to perform
p-type doping of ZnBeO and ZnMgBeO alloys. For N doped in
ZnBeO alloy, we show that the acceptor transition energies become
shallower as the number of the nearest neighbor Be atoms
increases. This is thought to be because of the reduction of
p-d repulsion. The NO acceptor transition
energies are deep in the ZnMgBeO quaternary alloy lattice-matched
to GaN substrate due to the lower valence band maximum. These
decrease slightly as there are more nearest neighbor Mg atoms
surrounding the N dopant. The important natural valence band
alignment between ZnO, MgO, BeO, ZnBeO, and ZnMgBeO quaternary
alloy is also investigated. |
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Keywords: | PACS" target="_blank">PACS 71 20 Nr Semiconductor compounds 71 55 Gs II-VI semiconductors 61 72 Bb Theories and models of crystal defects |
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