A Simulation Study of Electronic Device Designs for the Control of SiC Color Centers as Spin Qubits

Point defects in 4H silicon carbide (4H-SiC), such as the silicon vacancy, also known as color centers, offer considerable potential for quantum applications in the fields of quantum sensing as well as computing and communication. The latter two necessitate indistinguishable photons for entanglement swapping and consequently demand precise control over the electronic transition energies, i.e. emission and absorption wavelengths of color centers. One way to achieve this is through monolithic integration of electronic devices in combination with integrated photonics in 4H-SiC. This is considered a potential pathway for scalable quantum photonic integrated circuits. In this paper, we investigate the suitability of a signal-ground-modulator and a vertical pin diode in combination with a waveguide to (i) achieve local field strengths of 5 to 20 MV/m in the crystal’s c-direction, (ii) stabilize the charge state of the silicon vacancy by controlling the local Fermi level, (iii) meet the requirements for photonic single-mode operation, and (iv) minimize the absorption of the evanescent wave due to metal contacts. The findings of the electronic and optical simulations conducted with Synopsys Sentaurus and Ansys Lumerical suggest that the signal-ground-modulator, commonly used in integrated photonics, rarely attains the requisite field strength. In contrast, the vertical pin diode has the potential to meet these requirements even at reduced bias voltages. Furthermore, the intrinsic layer of the diode offers a wide region in which to host the color center in its optically active, negatively charged state.