Alessandro Rossi, Strathclyde University
Silicon carbide (SiC) has been used for decades for high-power and harsh-environment electronics. Hence, there exist reliable manufacturing processes for a range of devices such as transistors, diodes, switches etc. However, integrated electronics based on SiC is at a very embryonic stage due to high density of crystal defects inherently associated with the material growth and processing, which ultimately hampers system miniaturisation. More recently, some of these crystal defects have been used for quantum applications. For example, silicon vacancies and divacancies can function as radiative recombination centres and can be used to realise single-photon sources. Furthermore, they have paramagnetic nature and lend themselves to function as spin-based quantum bits, quantum memories and spin-photon interfaces. However, to date the vast majority of these quantum systems resides in bulky and barely processed substrates and are nearly exclusively accessible via optical scanning techniques due to the difficulty with functionalising the material at the nanoscale.
I will discuss our plans and recent progress towards the goal of building fully electrical quantum devices in SiC. I will show that we can control the creation of silicon vacancy ensembles via industry-compatible processes, such as ion implantation and thermal annealing. Our interest is in tuning the fabrication parameters to create shallow isolated defects within an intrinsic epi-layer, which would make it possible to couple charge and spin degrees of freedom to a metal-oxide-semiconductor device architecture for electrical readout. By using an in-situ gate electrode embedded into a LC tank resonator, single-defect detection can be attained by measuring the dispersive shift in the resonant frequency when tunnelling produces small capacitive perturbations, a technique known as gate-based reflectometry. I will discuss how we routinely use this technique for spin readout of both hole and electron quantum dots in silicon, as well as our plans to translate this technology for electrical readout of spin defects in SiC. This approach could provide the technological advance necessary for scalable quantum electronics and large-scale integration in SiC.