Material parameter calculation of semiconductor substrates via terahertz time-domain spectroscopy
In this study, terahertz time-domain spectroscopy (THz-TDS) was utilized to determine the refractive indices, n, and absorption coefficients, α, of semi-insulating gallium arsenide (SI-GaAs) and lightly doped n-type silicon (n-Si). Amplitude and phase information from the spectra of the transmitted THz signal were used to calculate for the material optical parameters. The obtained experimental value of refractive indices of SI-GaAs and n-Si at 1.25 THz were calculated to be 3.57 and 3.35, respectively. Meanwhile, the respective absorption coefficients of SI-GaAs and n-Si at 1.25 THz were also calculated to be 3.55 cm−1 and 7.79 cm−1. The experimental values of the samples' refractive indices and absorption coefficients are in close agreement with published reference values.