Vapor phase 6H and 4H SiC epitaxy for high-speed devices

Silicon carbide (SiC), a wide bandgap semiconductor, is currently being developed for enhanced high-power and high-temperature microwave devices. Silicon carbide wafers, now available at up to two-inch diameter with resistivities from 0.02 Ω-cm to 10⁷ Ω-cm, still exhibit features such as micropipes, surface scratches, and inclusions of other polytypes. Vapor phase epitaxy (VPE) of 6H and 4H SiC, typically performed between 1450 and 1600°C using silane and propane reagents, is impacted greatly by the quality of these wafers and the conditions used during in situ etching or the initial stages of growth. By optimizing growth conditions, device-quality homoepitaxial 6H and 4H-SiC has been grown with near specular morphology, background doping levels of less than 1×10¹⁴ cm^-3, and controlled n- and p-type doping from less than 5×10¹⁵ cm^-3 to greater than 1×10¹⁹ cm^-3