Identification of divacancy and silicon vacancy qubits in 6H-SiC

Abstract

Point defects in semiconductors are relevant for use in quantum technologies as room temperature qubits and single photon emitters. Among suggested defects for these applications are the negatively charged silicon vacancy and the neutral divacancy in SiC. The possible nonequivalent configurations of these defects have been identified in 4H-SiC, but for 6H-SiC the work is still in progress. In this paper, we identify the different configurations of the silicon vacancy and the divacancy defects to each of the V1-V3 and the QL1-QL6 color centers in 6H-SiC, respectively. We accomplish this by comparing results from ab initio calculations with experimental measurements for zero-phonon line, hyperfine tensor, and zero-field splitting.

Stabilization of point-defect spin qubits by quantum wells

“…Beside the already identified divacancy configurations (PL1-4 in 4H-SiC and QL1-6 in 6H-SiC) 7,24–26 , related color centers with unknown atomic configurations (PL5-7 in 4H-SiC and QL7-9 in 6H-SiC) have been recently reported 7,16,18,24,27 . Unlike to the regular divacancy defects, the additional color centers demonstrate robustness against photoionization effects 16 and optical spin contrast persisting up to room temperature 7,24,27 .…”

Silicon carbide color centers for quantum applications

“…The most studied defects are the neutral divacancy or V Si V C (0) and negatively Color centers in SiC plotted versus their observed ZPL by PL measurements and their spin ZFS from electron paramagnetic resonance (EPR) or optically detected magnetic resonance (ODMR) measurements (left) for spin defects with proved optical spin polarization. Among these the V Si [40] V C V Si , [41,42] the N C V Si [43,44] in various polytypes. In addition, some transition metal color centers such as Ti [45], V [45][46][47], and Mo [48].…”

“…Only recently the V Si (−) role as qubit and charge state have been fully identified by means of high-precision first-principles calculations and high-resolution EPR resonance measurements, as an isolated negatively charged silicon-vacancy and it is associated to so-called V1 line being a V (−) Si at h (hexagonal)-site and V2 a V (−) Si at k (cubic) site for 4H-SiC [40], as for 6H V (−) Si the V1 is an h-site, V2 is a k2 site and V3 a k1 site [42]. In figures 3(A)-(C) the comparison between the cubic 3C and hexagonal 4H and 6H polytype SiC stacking layers seen from the top along the main crystallographic axis c, where the atoms of Si and C are shown along axis c or off-axis in different cubic h sites or hexagonal sites-k. For a single vacancy, it is expected that it occupies one of the 2 sites in 4H and 3 sites in 6H, as such the ZPLs are 2 or 3, plus excited state doublet.…”

“…The defect labeled DV (0) [81] (figure 4(C)) quantum properties were studied in 4H-SiC and associated to the PL1-PL4 lines in [53,55,[82][83][84][85][86]. It is currently associated with an S=1 V Si V C (0) , with ZPLs corresponding to the 4 non-equivalent sites, as following, PL1 occupying the hh site, PL2 kk site, PL3 kh, and PL4 hk site [41,42]. ZPLs are in the range 1078-1132 nm with ZFS of 1.224-1.336 GHz in the ground state and 0.75-0.95 GHz in excited states.…”

“…The maximum ODMR signal by off-resonant optical excitation is<0.001. Its full identification has been recently proposed [42]. The defect labeled Ky5 is the divacancy in polytype 3C at 1127 nm is studied in [82,85].…”