Transport properties of polarization-induced 2D electron gases in epitaxial AlScN/GaN heterojunctions

• Published in: Applied physics letters 2022-11, Vol.121 (19)
• Main Authors: Casamento, Joseph, Nguyen, Thai-Son, Cho, Yongjin, Savant, Chandrashekhar, Vasen, Timothy, Afroz, Shamima, Hannan, Daniel, Xing, Huili (Grace), Jena, Debdeep
• Format: Article
• Language: English
• Subjects: Applied physics; Barrier layers; Cryogenic temperature; Electron gas; Gallium nitrides; Hall effect; Heterojunctions; Heterostructures; High electron mobility transistors; Interlayers; Lattice matching; Physics; Polarization; Room temperature; Semiconductor devices; Transport properties
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0108475

AlScN is attractive as a lattice-matched epitaxial barrier layer for incorporation in GaN high electron mobility transistors due to its large dielectric constant and polarization. The transport properties of polarization-induced two-dimensional (2D) electron gas of densities of ∼ 2 × 10 13/cm2 formed at the AlScN–GaN interface is studied by Hall-effect measurements down to cryogenic temperatures. The 2D electron gas densities exhibit mobilities limited to ∼300 cm2/V s down to 10 K at AlScN/GaN heterojunctions. The insertion of a ∼2 nm AlN interlayer boosts the room temperature mobility by more than five times from ∼300 cm2/V s to ∼ 1573 cm2/V s, and the 10 K mobility by more than 20 times to ∼6980 cm2/V s at 10 K. These measurements provide guidelines to the limits of electron conductivities of these highly polar heterostructures.