Electrometry by optical charge conversion of deep defects in 4H-SiC

TL;DR

This paper introduces an all-optical method using charge conversion in deep defects of 4H-SiC to detect high-frequency electric fields, providing a new tool for electrometry with high sensitivity and spatial resolution.

Contribution

The study demonstrates a novel optical charge conversion technique in 4H-SiC defects for high-frequency electric field sensing, expanding the capabilities beyond spin-based methods.

Findings

Achieved a sensitivity of ~41 (V/cm)^2 / √Hz in electric field detection.

Successfully mapped surface acoustic wave modes in a SiC mechanical resonator.

Operated effectively from cryogenic to room temperature.

Abstract

Optically-active point defects in various host materials, such as diamond and silicon carbide (SiC), have shown significant promise as local sensors of magnetic fields, electric fields, strain and temperature. Current sensing techniques take advantage of the relaxation and coherence times of the spin state within these defects. Here we show that the defect charge state can also be used to sense the environment, in particular high frequency (MHz-GHz) electric fields, complementing established spin-based techniques. This is enabled by optical charge conversion of the defects between their photoluminescent and dark charge states, with conversion rate dependent on the electric field (energy density). The technique provides an all-optical high frequency electrometer which is tested in 4H-SiC for both ensembles of divacancies and silicon vacancies, from cryogenic to room temperature, and with a measured sensitivity of ~41 (V/cm)**2 / $\sqrt{Hz}$. Finally, due to the piezoelectric character of SiC, we obtain spatial 3D maps of surface acoustic wave modes in a mechanical resonator.