Room-Temperature Photochromism of Silicon Vacancy Centers in CVD Diamond

Abstract

The silicon vacancy (SiV) center in diamond is typically found in three stable charge states, SiV0, SiV–, and SiV2–, but studying the processes leading to their formation is challenging, especially at room temperature, due to their starkly different photoluminescence rates. Here, we use confocal fluorescence microscopy to activate and probe charge interconversion between all three charge states under ambient conditions. In particular, we witness the formation of SiV0 via the two-step capture of diffusing, photogenerated holes, a process we expose both through direct SiV0 fluorescence measurements at low temperatures and confocal microscopy observations in the presence of externally applied electric fields. In addition, we show that continuous red illumination induces the converse process, first transforming SiV0 into SiV– and then into SiV2–. Our results shed light on the charge dynamics of SiV and promise opportunities for nanoscale sensing and quantum information processing.

Fast optoelectronic charge state conversion of silicon vacancies in diamond

“…For SnV, the consensus has converged more toward interaction with the VB under illumination in the visible (13), and our results support this hypothesis also for SiV. While SiV − is a bright emitter, SiV 2− is optically dark and SiV 0 emits at a different frequency (19). The charge state depends on the nature and concentration of proximal defects, the illumination scheme, and the proximity of electric contacts that influence carrier capture and ionization rates via the electric fields they generate.…”

“…The charge state depends on the nature and concentration of proximal defects, the illumination scheme, and the proximity of electric contacts that influence carrier capture and ionization rates via the electric fields they generate. Recently, Wood et al ( 19 ) used confocal fluorescence microscopy to show that the SiV charge state can be changed by diffusing and drifting photogenerated holes such that the spatial distance of the G4V to the points of illumination is also a very relevant parameter. Several strategies have previously been proposed to control the SiV charge state, including doping ( 20 ), chemical surface treatments ( 21 , 22 ), and integration into p-i-n diodes to control the position of the quasi-Fermi level ( 23 , 24 ).…”

Effectively enhancing silicon-vacancy emission in a hybrid diamond-in-pit microstructure

“…However, the main reason for the enhancement of the SiV emission observed in our experiments, we believe, is related to the active switching of the SiV centers from the dark to the bright state stimulated by plasmon modes of the ND-nanopit microstructure. The bright state corresponds to negatively charged SiV centers (SiV − ), while the dark state is associated with neutrally or doubly-charged centers (SiV 0 or SiV 2− ) [34][35][36][37][38]. The mechanism of switching to the bright state is partially confirmed by measuring the PL decay curves in our experiment.…”

SiV 0 centres in diamond: effect of isotopic substitution in carbon and silicon

“…In addition, there is another, neutral charge state of the SiV centre (SiV 0 ) that emits light in the near-infrared range at a wavelength of 946 nm, which is closer to the telecommunication wavelengths [29][30][31]. The SiV 0 centre is an attractive candidate for quantum memory, network and computing due to its unique optical properties for such purposes [32][33][34][35][36]. The SiV 0 has a four orders longer spin coherence time than SiV − (T 2 ≈ 0.945 ms at 20 K versus T 2 ≈ 35 ns at 4.5 K, respectively), more stable optical transitions than NV − and longer-lived nuclear spin (T 2n ≈ 0.45 s) [33].…”