arXiv subjects

Danial Shafizadeh

Publications and source records attributed to Danial Shafizadeh.

3 recordsLinked to original sources

arXiv2026

Spin-active chlorine-related centers in 4H-SiC with telecom-band emissions

A photoluminescence (PL) and magnetic resonance investigation of a defect in chlorine-implanted 4H-SiC is presented. This Cl-related center emits light at telecom wavelengths with zero-phonon lines in the range 1350-1540 nm. Its four configurations exhibit stable PL spectra characterized by narrow zero-phonon lines. For the two configurations that emit light at the C-band, a Debye-Waller factor in the range 22-25% is estimated. Optically detected magnetic resonance confirms that the Cl-related center is spin active and stable at room temperature with the zero-field splitting in the range of 1.0-1.4 GHz. The combined optical and spin properties suggest this center to be a highly promising candidate for scalable quantum networks.

quant-ph↗

arXiv2023

Selection rules in the excitation of the divacancy and the nitrogen-vacancy pair in 4H- and 6H-SiC

In this study, we address the selection rules with respect to the polarization of the optical excitation of two colour centres in 4H-SiC and 6H-SiC with potential for applications in quantum technology, the divacancy and the nitrogen-vacancy pair. We show that the photoluminescence (PL) of the axial configurations of higher symmetry (C3v) than the basal ones (C1h) can be cancelled using any excitation (resonant or non-resonant) with polarization parallel to the crystal axis (EL||c). The polarization selection rules are determined using group-theoretical analysis and simple physical arguments showing that phonon-assisted absorption with EL||c is prohibited despite being formally allowed by group theory. A comparison with the selection rules for the silicon vacancy, another defect with C3v symmetry, is also carried out. Using the selection rules, we demonstrate selective excitation of only one basal divacancy configuration in 4H-SiC, the P3 line and discuss the higher contrast and increased Debye-Waller factor in the selectively excited spectrum.

quant-ph↗

arXiv2022

Exhaustive characterization of modified Si vacancies in 4H-SiC

The negatively charged silicon vacancy ($\mathrm{V_{Si}^-}$) in silicon carbide is a well-studied point defect for quantum applications. At the same time, a closer inspection of ensemble photoluminescence and electron paramagnetic resonance measurements reveals an abundance of related but so far unidentified signals. In this study, we search for defects in 4H-SiC that explain the above magneto-optical signals in a defect database generated by Automatic Defect Analysis and Qualification (ADAQ) workflows. This search reveals only one class of atomic structures that exhibit silicon-vacancy-like properties in the data: a carbon antisite ($\mathrm{C_{Si}}$) within sub-nanometer distances from the silicon vacancy only slightly alters the latter without affecting the charge or spin state. Such a perturbation is energetically bound. We consider the formation of $\mathrm{V_{Si}^-+C_{Si}}$ up to 2 nm distance and report their zero phonon lines and zero field splitting values. In addition, we perform high-resolution photoluminescence experiments in the silicon vacancy region and find an abundance of lines. Comparing our computational and experimental results, several configurations show great agreement. Our work demonstrates the effectiveness of a database with high-throughput results in the search for defects in quantum applications.

cond-mat.mtrl-sci↗