The dielectric properties of some ceramic substrate materials at terahertz frequencies

Abstract

The terahertz (THz) dielectric constant (εr') and dielectric loss tangent (tanδ) of the commercial LTCC materials (Ferro A6M and DuPont 951), Al2O3 (ceramic and single crystal), AlN and β-Si3N4 ceramics were measured using a vector network analyzer (VNA) over the frequency range of 140–220 GHz and a time-domain spectrometer (TDS) from 0.2 to 1.0 THz. The results from the two instruments are compared with the literature and show good agreement and consistency. For Ferro A6M, εr' = 6.06, tanδ = 0.012 at 1.0 THz. For DuPont 951, εr' = 7.67, tanδ = 0.097 at 1.0 THz. For Al2O3 ceramic and single crystal, the measured THz dielectric properties are consistent with the reported works. The dielectric constant of AlN (εr' = 8.85) and β-Si3N4 (εr' = 8.41) ceramics in the THz region is a little lower than those reported for the MHz to GHz region. These results provide valuable and much needed reference information for device designers and material scientists.