[7a-P05-1~80] 17 Nanocarbon and Two-Dimensional Materials (Poster)

English Presentation

[7a-P05-64] Polarization-Induced 2DEG and 2DHG Probed by Terahertz Spectroscopy

〇Verdad Agulto¹, Shuang Liu¹, Kosaku Kato¹, Thanh Nhat Khoa Phan¹, Yu-Hsin Chen², Chuan Chang², Joseph Dill², Jimy Encomendero², Debdeep Jena², Huili Grace Xing², Jia Wang³, Haitao Wang³, Hiroshi Amano³, Makoto Nakajima¹ (1.Univ. of Osaka, 2.Cornell Univ., 3.Nagoya Univ.)

Keywords:

two-dimensional carrier gas,wide-bandgap semiconductor,terahertz spectroscopy

High-electron-mobility transistors (HEMTs) based on AlN quantum well (QW) structures show strong potential for high-frequency power device applications. These structures feature a GaN QW layer sandwiched between AlN buffer and barrier layers. A two-dimensional electron gas (2DEG) is induced by the strong polarization discontinuity at the AlN/GaN interface and is effectively confined within the GaN QW due to the large band offsets. AlN/GaN/AlN HEMTs typically exhibit limited Hall mobilities of ~800 cm² V^-1 s^-1, smaller compared to conventional AlGaN/GaN HEMTs which achieve high room-temperature 2DEG mobilities of ~1500 cm² V^-1 s^-1. This limitation is attributed to interface roughness scattering and possible Coulomb drag from a two-dimensional hole gas (2DHG) likely present at the GaN/AlN buffer interface. In this work, we investigate the coexistence of 2DHG and 2DEG channels in AlN/GaN/AlN QW structures and their transport properties using terahertz spectroscopy.