Temperature dependence of the AB-lines and Optical Properties of the Carbon-Antisite Vacancy Pair in 4H-SiC

TL;DR

This study investigates the temperature dependence and optical properties of the carbon antisite-vacancy pair in 4H-SiC, revealing discrepancies with previous assignments of the AB photoluminescence lines and suggesting the need for further research.

Contribution

It provides new experimental measurements and computational analysis of the CAV defect, challenging prior understanding of the AB-line origins in 4H-SiC.

Findings

AB-lines consist of three non-thermally activated lines, not four

CAV defect may emit in the near-infrared telecom band in certain charge states

Computational results do not fully match the AB-line optical transitions

Abstract

Defects in semiconductors have in recent years been revealed to have interesting properties in the venture towards quantum technologies. In this regard, silicon carbide has shown great promise as a host for quantum defects. In particular, the ultra-bright AB photoluminescence lines in 4H-SiC are observable at room temperature and have been proposed as a single-photon quantum emitter. These lines have been previously studied and assigned to the carbon antisite-vacancy pair (CAV). In this paper, we report on new measurements of the AB-lines' temperature dependence, and carry out an in-depth computational study on the optical properties of the CAV defect. We find that the CAV defect has the potential to exhibit several different zero-phonon luminescences with emissions in the near-infrared telecom band, in its neutral and positive charge states. However, our measurements show that the AB-lines only consist of three non-thermally activated lines instead of the previously reported four lines, meanwhile our calculations on the CAV defect are unable to find optical transitions in full agreement with the AB-line assignment. In the light of our results, the identification of the AB-lines and the associated room temperature emission require further study.