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Electronic structure and optical properties of Si, Ge and diamond in the lonsdaleite phase
Journal article   Peer reviewed

Electronic structure and optical properties of Si, Ge and diamond in the lonsdaleite phase

Amrit De and Craig E Pryor
Journal of physics. Condensed matter, Vol.26(4), pp.045801-045801
01/29/2014
DOI: 10.1088/0953-8984/26/4/045801
PMID: 24592487
url
https://arxiv.org/pdf/1210.7392View
Open Access

Abstract

Crystalline semiconductors may exist in different polytypic phases with significantly different electronic and optical properties. In this paper, we calculate the electronic structure and optical properties of diamond, Si and Ge in the lonsdaleite (hexagonal diamond) phase using a transferable model empirical pseudopotential method with spin-orbit interactions. We calculate their band structures and extract various relevant parameters. Differences between the cubic and hexagonal phases are highlighted by comparing their densities of states. While diamond and Si remain indirect gap semiconductors in the lonsdaleite phase, Ge transforms into a direct gap semiconductor with a much smaller bandgap. We also calculate complex dielectric functions for different optical polarizations and find strong optical anisotropy. We further provide expansion parameters for the dielectric functions in terms of Lorentz oscillators.
band structures empirical pseudopotentials optical dielectric functions semiconductors

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