4H-Silicon carbide membranes as an enabling technology for point defect-device integration

4H-Silicon Carbide (4H-SiC) is a wide bandgap semiconductor that has a broad range of applications from high power electronics to MEMS, and more recently in studying solid state point defects (also known as color centers) for quantum engineering. Crucial to such applications is integration into devices, allowing us to control and readout their optical and spin properties. An important step in fabrication lies in suspending the devices: for instance, suspending nanophotonic cavities is critical for optical mode confinement and thus strong cavity-defect coupling. We have recently developed a photoelectrochemical etching process that allows high-precision dopant-selective etching of large scale membranes with atomically-smooth surfaces (1). Here, we apply that technique to first create large areas of suspended undoped 4H-SiC, and then utilize these membranes to fabricate devices. Electron beam lithography on membrane structures offers advantages in reduction of proximity effects that constrain the density and minimum feature sizes achievable. We demonstrate the versatility in this new “bottom-up” fabrication approach by fabricating crossbeam cavities, tapered fiber cavities, and mechanical cavities for coupling to color centers.