Room-temperature near-infrared silicon carbide nanocrystalline emitters based on optically aligned spin defects

TL;DR

This paper demonstrates the fabrication of silicon carbide nanocrystals with optically aligned spin defects that emit in the near-infrared at room temperature, enabling bio-imaging and quantum sensing applications.

Contribution

It reports the first observation of room-temperature spin resonances in SiC nanocrystals, expanding their potential for bio-imaging and sensing.

Findings

Silicon carbide nanocrystals can emit near-infrared photoluminescence.

Room-temperature spin resonances of silicon vacancies are detected in SiC nanocrystals.

Nanocrystals can be used as luminescent markers and sensors.

Abstract

Bulk silicon carbide (SiC) is a very promising material system for bio-applications and quantum sensing. However, its optical activity lies beyond the near infrared spectral window for in-vivo imaging and fiber communications due to a large forbidden energy gap. Here, we report the fabrication of SiC nanocrystals and isolation of different nanocrystal fractions ranged from 600 nm down to 60 nm in size. The structural analysis reveals further fragmentation of the smallest nanocrystals into ca. 10-nm-size clusters of high crystalline quality, separated by amorphization areas. We use neutron irradiation to create silicon vacancies, demonstrating near infrared photoluminescence. Finally, we detect, for the first time, room-temperature spin resonances of these silicon vacancies hosted in SiC nanocrystals. This opens intriguing perspectives to use them not only as in-vivo luminescent markers, but also as magnetic field and temperature sensors, allowing for monitoring various physical, chemical and biological processes.