Semiconductor color-center structure and excitation spectra: Equation-of-motion coupled-cluster description of vacancy and transition-metal defect photoluminescence

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.

Single photon detection system for visible and infrared spectrum range

“…This moves the single molecule photon source away from being used in any practical (commercial) not only experimental realization. Another candidate for single-photon source which is characterized by the polarization controlling of emitted photons are color centers [56,57]. Based on defects in crystalline structure, primarily nitrogen-vacancies (NV) in diamonds, a color center has broad absorption and emission spectrum, with the central lines at 575 nm and 637 nm, respectively [58,59].…”

The elusive photocatalytic water splitting reaction using sunlight on suspended nanoparticles: is there a way forward?

“…Since in photocatalytic reactions charge carriers' lifetime is an intrinsic part of the reaction rate, TD-DFT studies are very much needed, yet at present because of demanding computational resources, they are seldom conducted, mostly on clusters. [64][65][66] Another technique that is gaining momentum for measurement of charge carriers is pump-probe transient absorption spectroscopy (TAS). [67][68][69] While this technique is well developed for molecular studies as well as nanoparticles, it is not as well studied for single crystals and well defined thin films (epitaxy).…”

The Lowest-Energy Isomer of C2Si2H4 Is a Bridged Ring: Reinterpretation of the Spectroscopic Data Based on DFT and Coupled-Cluster Calculations

“…Mapping interstellar silicon reaction networks is one application [49], as C 2 Si 2 H 4 may result from bimolecular collisions between the highly-abundant acetylene and its silicon-based analog disilyne. This bimolecular reaction and subsequent isomerization can also be considered as a model system for understanding preferred bonding configurations in coordinate complexes [50], bulk silicon surface-adsorption [51], and defect-inclusion processes [52].…”