Convergence of Ground and Excited State Properties of Divacancy Defects in 4H-SiC with Computational Cell Size

Report No. ARL-TR-8313
Authors: Ariana Beste; DeCarlos E Taylor
Date/Pages: March 2018; 44 pages
Abstract: Deep defect centers in semiconductors show electronic behavior that can be exploited in quantum computing applications. In particular, the neutral divacancy defect in 4H-SiC has been considered as a potential qubit material that is individually addressable in the near IR. To study the divacancy defect computationally, the behavior of properties relevant to the function of the material as a qubit with respect to computational parameters needs to be established. We used density functional theory to compute defect formation energies of the neutral and charged hh divacancy with corresponding charge transition levels, the position of the highest occupied, localized defect state within the band gap, and excitation energies for the 3A to 3E transition (absorption, zero phonon lines, and emission), which is essential for optical initialization and read-out. We investigated the convergence of these properties with respect to computational cell size and studied the effects of lattice relaxation and dispersion corrections. Based on our results, we recommend computational parameters for future computational work.
Distribution: Approved for public release
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Last Update / Reviewed: March 1, 2018