Characterization of the electrical properties of an InN epilayer using terahertz time-domain spectroscopic ellipsometry

We demonstrate the measurement of electrical properties of InN layers grown by RF-MBE using terahertz time-domain spectroscopic ellipsometry (THz-TDSE). Dependences of carrier density and mobility on InN film thickness are characterized using THz-TDSE. It is found that these electrical properties of the InN films are improved with the increase in the film thickness. Although the results obtained by Hall effect measurement also show the same tendency, the electrical properties of InN obtained by THz-TDSE is superior to those by Hall effect measurement. In addition, we also apply a two-layer model for THz-TDSE measurement to analyze the electrical properties of the bulk InN region and the surface electron accumulation layer independently. The mobility ranging from 50 to 140 cm(2) V-1 s(-1) are obtained for the surface electron accumulation layer of InN. (C) 2019 The Japan Society of Applied Physics