Photoexcitation-assisted EDMR on SiC JFETs for quantum sensing applications

Electrically detected magnetic resonance (EDMR) is a powerful tool to interrogate quantum phenomena in semiconductors, e.g., to facilitate microelectronic sensors such as magnetometers. However, efforts to increase EDMR magnetometer sensitivity into the critical single-digit nT/Hz range have stalled, prompting recent electro-optical pumping schemes. Notable advancements in enhancing the EDMR response in silicon carbide (SiC) devices exposed to ultraviolet (UV) light have been reported. We investigate the interplay between UV excitation and bias voltage in UV-pumped EDMR using a 4H-SiC junction field-effect transistor (JFET). We identify two sensitivity-improving operational regimes: (i) spin-dependent recombination (SDR)-dominated signal enhancement in the standard forward-bias range, and (ii) noise reduction enabled by UV-induced shifting of the device open-circuit voltage UOC. While our sensor clearly benefits from signal enhancement, we also observe a saturation of this effect at higher biases and excitation powers. By contrast, operation in the UOC regime emerges as a promising alternative, where we report a record EDMR contrast, exceeding 2%. We achieve a maximum sensitivity of 30 nT/Hz, on par with record performances reported for EDMR magnetometers. This is projected to reach a single-digit nT/Hz figures of merit at higher photoexcitation power. Our findings highlight the potential of UV-enhanced EDMR, despite saturation limits in the forward-bias regime, and establish photoexcited EDMR magnetometers as a competitive alternative to state-of-the-art magnetic field sensors.