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Issue 11, 2019
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Band alignment in quantum wells from automatically tuned DFT+U

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Abstract

Band alignment between two materials is of fundamental importance for a multitude of applications. However, density functional theory (DFT) either underestimates the bandgap – as is the case with the local density approximation (LDA) or generalized gradient approximation (GGA) – or is highly computationally demanding, as is the case with hybrid-functional methods. The latter can become prohibitive in electronic-structure calculations of supercells which describe quantum wells. We propose to apply the DFT+U method, with U for each atomic shell being treated as set of tuning parameters, to automatically fit the bulk bandgap and the lattice constant, and then use the thus obtained U parameters in large supercell calculations to determine the band alignment. We apply this procedure to InP/In0.5Ga0.5As, In0.5Ga0.5As/In0.5Al0.5As and InP/In0.5Al0.5As quantum wells, and obtain good agreement with experimental results. Although this procedure requires some experimental input, it provides both meaningful valence and conduction band offsets while, crucially, lattice relaxation is taken into account. The computational cost of this procedure is comparable to that of LDA. We believe that this is a practical procedure that can be useful for providing accurate estimates of band alignments between more complicated alloys.

Graphical abstract: Band alignment in quantum wells from automatically tuned DFT+U

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Article information


Submitted
08 Jan 2019
Accepted
21 Feb 2019
First published
22 Feb 2019

Phys. Chem. Chem. Phys., 2019,21, 5966-5973
Article type
Paper

Band alignment in quantum wells from automatically tuned DFT+U

G. Kolesov, C. Lin, A. Knyazev, K. Kojima, J. Katz, K. Akiyama, E. Nakai and H. Kawahara, Phys. Chem. Chem. Phys., 2019, 21, 5966
DOI: 10.1039/C9CP00122K

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