Ligand hyperfine interactions at silicon vacancies in 4H-SiC

Nguyen Tien Son,Ivan G Ivanov,Pontus Stenberg,Takeshi Ohshima,Jawad Ul Hassan,Valdas Jokubavicius

doi:10.1088/1361-648x/ab072b

Abstract

The negative silicon vacancy () in SiC has recently emerged as a promising defect for quantum communication and room-temperature quantum sensing. However, its electronic structure is still not well characterized. While the isolated Si vacancy is expected to give rise to only two paramagnetic centers corresponding to two inequivalent lattice sites in 4H–SiC, there have been five electron paramagnetic resonance (EPR) centers assigned to in the past: the so-called isolated no-zero-field splitting (ZFS) center and another four axial configurations with small ZFS: TV1a, TV2a, TV1b, and TV2b. Due to overlapping with 29Si hyperfine (hf) structures in EPR spectra of natural 4H–SiC, hf parameters of TV1a have not been determined. Using isotopically enriched 4H-28SiC, we overcome the problems of signal overlapping and observe hf parameters of nearest C neighbors for all three components of the S = 3/2 TV1a and TV2a centers. The obtained EPR data support the conclusion that only TV1a and TV2a are related to and the two configurations of the so-called isolated no-ZFS center, (I) and (II), are actually the central lines corresponding to the transition |−1/2〉 ↔ |+1/2〉 of the TV2a and TV1a centers, respectively.

Highlights

The silicon vacancy (VSi) in silicon carbide (SiC) was first identified by electron paramagnetic resonance (EPR) in 3C-SiC [1, 2]
In natural SiC, the R1 signal cannot be resolved from the hf structure with a splitting of ~3 G due to the interaction between the electron spin and the nuclear spin of one 29Si atom occupying one of the next nearest neighbors (NNN) 12 Si sites
The reason is that in an S = 3/2 system with three unpaired electrons, there are three spin pairs (S1S2, S2S3, S3S1), whose dipole–dipole interaction in high symmetry crystals may partly cancel each other resulting in a small contribution to the zero-field splitting (ZFS) tensor. (For an S = 1 system with only one spin pair there is no such cancelation and the ZFS is expected to be large.) with S = 3/2, the R1, R2, TV1b and TV2b centers will have their central line (CL) overlapping with the CL of TV1a and TV2a

Summary

Introduction

The silicon vacancy (VSi) in silicon carbide (SiC) was first identified by electron paramagnetic resonance (EPR) in 3C-SiC [1, 2]. Wimbauer and co-workers observed this center in 4H- and

Present address

Experiment

Results and discussion

Summary