Estimation of carrier density of wide bandgap semiconductor β-Ga2O3 single crystals by THz reflectance measurement

In order to estimate carrier density on wide bandgap semiconductor β-Ga₂O₃, we made a measurement of THz reflectance spectra of β-Ga₂O₃ samples by using a THz time-domain spectroscopic method. The tails of reflectance structures were shifted to higher energy side with increasing the carrier density. We treated the structure was caused by plasmon, and calculated the carrier density of each samples. The carrier densities obtained by the THz reflection measurements showed a good agreement with the results by Hall-effect measurements. These results indicated that THz spectroscopy is a useful method to estimate the carrier density of β-Ga₂O₃ samples.