Paper Review

Noncontact Measurement of PhysicalProperties of Semiconductors by Terahertz Time-Domain Spectroscopic Ellipsometry

Original Paper | “Measurement of the dielectric constant of thin films by terahertz time-domainspectroscopic ellipsometry,” Optics Letters, Vol. 36, No. 2, pp265-267 (2011)

Naoki Matsumoto, Tadasu Hosokura, Takeshi Nagashima*, Masanori Hangyo* [*Institute of Laser Engineering, Osaka University]
[The lead author received the best presentation award in connection with this paper at the 30th Annual Meeting of Laser Society of Japan.]

Terahertz (“THz”) light is light which has frequencies ranging from approximately 100GHz to 10 THz, the middle of the extremely high frequency waves and infrared light. Free electrons in a semiconductor resonate with the light in this frequency band, and their responses are reflected in dielectric properties, which are measured in the THz band, thereby being able to gain electrical-physical properties such as carrier density, mobility and the like. Our group has established THz time-domain spectroscopic ellipsometry which measures dielectric properties of a sample material based on the polarization properties of the THz light reflected from the sample. This method can measure electrical-physical properties without contacting the sample material and preprocessing to form electrodes, which were necessary in the past. Hence, this technology may contribute to the swift measurement of properties of nitride semiconductors, SiC, etc, which have been under development as next generation semiconductors.