Papers by Author: Hiromasa Ito

Abstract: THz imaging was performed in 2 s intervals with 1 mm resolution on a 3 in., 0.42 mm thick, as-cut n-type Silicon Carbide wafer. Carrier density, relaxation time, mobility, and resistivity obtained from imaging results are 0.91 × 10¹⁸ cm^-3, 4.36 × 10^-14 s, 218 cm²V^-1s^-1, and 3.14 × 10^-2 Ωcm, respectively. Compared with the standard values provided by the manufacturers, the results suggest that THz imaging has reliable precision and accuracy.

Abstract: The reflectance around the longitudinal optical (LO) phonon frequency in the terahertz region changes with the carrier density of silicon carbide (SiC), while the reflectance around the transverse optical (TO) phonon frequency remains constantly high. The relative reflectance obtained from the reflectance at the two frequencies related to the TO and LO phonon was evaluated as a function of the carrier density of SiC. Two waves around these phonon frequencies can be generated easily using a tunable terahertz source. Nondestructive imaging of the carrier density of cubic SiC (3C-SiC) at the rate of 1 s per point was carried out successfully using this tunable terahertz source.