In recent years, alloy electronic structure calculations based on supercell Brillouin zone unfolding have become popular. There are a number of formulations of the method which on the surface might appear different. Here we show that a discrete real-space description, based on discrete Fourier transforms, is fully general. Furthermore, such an approach can more easily show the effects of alloy scattering. We present such a method for treating the random alloy problem. This treatment features straightforward mathematics and a transparent physical interpretation of the calculated effective (i.e., approximate) energy bands. © 2016 Elsevier B.V. All rights reserved.

Arvind Ajoy

Department of Electrical Engineering

T.B. Boykin

H. Ilatikhameneh

M. Povolotskyi

G. Klimeck

Fulltext

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

Physica B: Condensed Matter

Thermal properties are of great interest in modern electronic devices and nanostructures. Calculating these properties is straightforward when the device is made from a pure material, but problems arise when alloys are used. Specifically, only approximate band structures can be computed for random alloys and most often the virtual crystal approximation (VCA) is used. Unfolding methods [Boykin, Kharche, Klimeck, and Korkusinski, J. Phys.: Condens. Matter 19, 036203 (2007)10.1088/0953-8984/19/3/036203] have proven very useful for tight-binding calculations of alloy electronic structure without the problems in the VCA, and the mathematical analogy between tight-binding and valence-force-field approaches to the phonon problem suggests they be employed here as well. However, there are some differences in the physics of the two problems requiring modifications to the electronic-structure approach. We therefore derive a phonon alloy band-structure (vibrational-mode) approach based on our tight-binding electronic-structure method, modifying the band-determination method to accommodate the different physical situation. Using the method, we study In(x)Ga(1-x)As alloys and find very good agreement with available experiments. © 2014 American Physical Society.

Physical Review B - Condensed Matter and Materials Physics

Brillouin zone unfolding method for effective phonon spectra

Complex bands k(E) in a semiconductor crystal, along a general direction n, can be computed by casting Schrödingers equation as a generalized polynomial eigenvalue problem. When working with primitive lattice vectors, the order of this eigenvalue problem can grow large for arbitrary n. It is, however, possible to always choose a set of non-primitive lattice vectors such that the eigenvalue problem is restricted to be quadratic. The complex bands so obtained need to be unfolded onto the primitive Brillouin zone. In this paper, we present a unified method to unfold real and complex bands. Our method ensures that the measure associated with the projections of the non-primary wavefunction onto all candidate primary wavefunctions is invariant with respect to the energy E. © 2012 IOP Publishing Ltd.

Journal of Physics Condensed Matter

Brillouin zone unfolding of complex bands in a nearest neighbour tight binding scheme

Perturbation analysis on large band gap bowing of dilute nitride semiconductors

New Journal of Physics

A general group theoretical method to unfold band structures and its application

Physical Review B

Effects of extrinsic and intrinsic perturbations on the electronic structure of graphene: Retaining an effective primitive cell band structure by band unfolding

Unfolding and effective bandstructure calculations as discrete real- A nd reciprocal-space operations

Journal	Data powered by TypesetPhysica B: Condensed Matter
Publisher	Data powered by TypesetElsevier B.V.
ISSN	09214526