[12p-N405-1~11] 4.6 Terahertz Photonics

▼ [12p-N405-4] Measurement of Optically Dense Semiconductor with 10²⁰ cm^-3 Carrier Density by Terahertz Time-Domain Ellipsometry

〇(P)Verdad Canila Agulto¹, Toshiyuki Iwamoto², Hideaki Kitahara¹, Kazuhiro Toya¹, Valynn Katrine Mag-usara¹, Masayuki Imanishi¹, Yusuke Mori¹, Masashi Yoshimura¹, Makoto Nakajima¹ (1.Osaka University, 2.PNP)

Keywords:terahertz, ellipsometry, semiconductor

Terahertz (THz) time-domain ellipsometry measures the complex amplitude ratio of p- and s-polarizations reflected from a material. It is a reference-free measurement technique which is an advantage over THz time-domain spectroscopy. This study presents a THz ellipsometry system that offers a significantly higher precision than the conventional THz ellipsometry method. With the improved system, high carrier concentrations beyond the typical measurable range by THz time-domain spectroscopy can be evaluated. To demonstrate, GaN single crystals with different carrier densities up to 10²⁰ cm^-3 were investigated. We show that the carrier density and mobility parameters can be obtained accurately even at very high carrier concentrations. Thus, our system extends the usability of THz waves for the characterization of optically dense semiconductors and is applicable to both thick wafers and thin films on substrates.