Document Type

Article

Publication Date

2018

Abstract

Valence excitation spectra are computed for deep-center silicon-vacancy defects in 3C, 4H, and 6H silicon carbide (SiC), and comparisons are made with literature photoluminescence measurements. Optimizations of nuclear geometries surrounding the defect centers are performed within a Gaussian basis-set framework using many-body perturbation theory or density functional theory (DFT) methods, with computational expenses minimized by a QM/MM technique called SIMOMM. Vertical excitation energies are subsequently obtained by applying excitation-energy, electron-attached, and ionized equation-of-motion coupled-cluster (EOMCC) methods, where appropriate, as well as time-dependent (TD) DFT, to small models including only a few atoms adjacent to the defect center. We consider the relative quality of various EOMCC and TD-DFT methods for (i) energy-ordering potential ground states differing incrementally in charge and multiplicity, (ii) accurately reproducing experimentally measured photoluminescence peaks, and (iii) energy-ordering defects of different types occurring within a given polytype. The extensibility of this approach to transition-metal defects is also tested by applying it to silicon-substituted chromium defects in SiC and comparing with measurements. It is demonstrated that, when used in conjunction with SIMOMM-optimized geometries, EOMCC-based methods can provide a reliable prediction of the ground-state charge and multiplicity, while also giving a quantitative description of the photoluminescence spectra, accurate to within 0.1 eV of measurement for all cases considered.
Abstract ©2018 American Physical Society

Comments

This record sources the open access CHORUS-furnished accepted manuscript (post-print) version of the article. A 12-month embargo was observed for this posting in accordance with the publisher and the research funding body.

The publisher version of record is a subscription-access article, appearing as cited below in volume 97 of Physical Review B, hosted at APS. Readers outside of AFIT will need to access the article through their own digital subscription to that periodical.
AFIT readers can reach the final article through AFIT Off-Campus Access.

DOI

10.1103/physrevb.97.115108

Source Publication

Physical Review B

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