Measurements of Complex Permittivity and Loss Tangent of Silicon Carbide at Millimeter Wavelengths

High purity semi-insulating 4H-SiC is highly desirable for SiC MESFET and GaN HEMT based power microwave devices. With the presented measurement techniques, namely cavity-length variation technique of open resonator operating at 60GHz, together with dispersive Fourier transform spectroscopy (DFTS), we successfully carried out the precise dielectric measurements of a pair of high purity semi-insulating 4H-SiC wafer specimens. Excellent agreement was obtained between two experimental systems. Therefore, it proves the versatility and accuracy of our established measurement techniques.