Wavelength dependent electrical readout of spin ensembles in thin-film silicon carbide on insulator platform

Abstract

We report electrical spin state readout and coherent control of a small ensemble (<450) of silicon vacancies in a silicon carbide-on-insulator (SiCOI) platform, with excitation wavelengths from 780 to 990 nm. Demonstrating for the first time spin state readout well beyond the zero phonon line of the V2 silicon vacancies. By implementing photoelectrical detection of magnetic resonance (PDMR) in thin-film SiCOI, we merge a scalable and optics-free spin readout technique together with a promising platform for scalable and CMOS-compatible integrated photonics. Furthermore, we provide a comparison of optical and electrical readout between bulk SiC and thin-film SiCOI, revealing that our thin-film processing has no significant effect on the bulk T2 time of ~ 7 microseconds. These results establish SiCOI as a versatile platform for not only integrated photonics but also electronic and spin-based devices for scalable quantum technologies over a wide range of excitation wavelengths.

Figures (4)

• Figure 1: Spin quartet energy states of the $V_{\mathrm{Si}}^{-}$ with the optical transition of 1.35 eV between ground and excited state of the $V_{\mathrm{Si}}^{-}$. Green arrows indicate the charge cycling. Photon-induced photocurrent from the defect is enabled by electron generation in the conduction band via two-photon absorption and photon-induced hole generation in the valence band.
• Figure 2: Confocal photocurrent scan (A,B) of the 4H-SiCOI device at 23 mW, 10 V bias and 870 nm under both focused (max 1.2 nA) and de-focused (max 0.8 nA) excitation conditions. The larger spot size in (B) demonstrates a broader distribution of photocurrent intensity. A microscope photo (C) of the electrode device covered in spin-on-glass and the measurement configuration shown in (D).
• Figure 3: Measured pulsed PDMR and pulsed ODMR in a 1.3 µm thin-film SiCOI device (D) and bulk 500 µm sample (A). All electrical measurements performed at 8 V bias, 890 nm and 45 mW. Electrical Rabi oscillations are observed with contrast $\approx$ 0.01% for both bulk (B) and thin film (E). Optical $T_2$ Hahn echo measurement (C, F) demonstrated coherence times of $\approx$ 7 µs for the thin film and bulk.
• Figure 4: Wavelength dependence of Rabi contrast in 1 µm thin-film 4H-SIC on SiO$_2$. Each data point is one Rabi period, fitted to a decaying sine function. Rabi is measured optically with 2 $\pm$ 0.5 mW laser power up to the 900LP dichroic filter limit and electrically with 40 mW $\pm 5$ mW to 960 nm and 40 to 70 mW up to 990 nm until the measured photocurrent reached the dark current. Optical error is directly from the fit and electrical error is the 5% variation from experiment stability combined with the fit error.