Terahertz monolithic integrated waveguide transmission lines based on wide bandgap semiconductor materials

In this paper, terahertz monolithic integrated waveguide (TMIW) transmission lines (TLs) are analyzed and fabricated based on wide bandgap semiconductor materials. The ignored parameters of TLs at low frequencies, such as the via-hole shape, the titanium/gold thickness and roughness, and the micropipe effect of material, are especially investigated based on the semiconductor fabrication technique and the terahertz-wave theory. Subsequently, the fine optimized TMIW-TL and the transition to grounded coplanar waveguide are fabricated. The measurement shows that the attenuation constant of a TL is as low as 0.19 dB/λ_g at 220 GHz. The proposed TMIW can provide electrical performance similar to the conventional air-filled waveguide, while it has only 10% of the volume, which indicates a great potential for future terahertz integrated systems.