Ultrahigh Dielectric Permittivity in Ultrathin 2D β-Ga<sub>2</sub>O<sub>3</sub> for Advanced Dielectric Applications.

Hu, Xianyu; Liu, Zixiong; Wang, Xinglong; Guo, Qing; Feng, Xiyuan; Zhong, Yunlei · Nano Lett · 2026

basic_science · Level V

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Abstract

The continuous scaling of semiconductor devices necessitates the integration of high-permittivity (high-<i>k</i>) dielectrics to maintain gate control and reduce power consumption. Here, we report an ultrahigh dielectric constant (<i>k</i>) of ∼150 in ultrathin (10 nm) β-gallium oxide (β-Ga<sub>2</sub>O<sub>3</sub>) metal-insulator-metal capacitors. Photoresponse and microstructural analyses link the giant permittivity to an oxygen vacancy (V<sub>O</sub>)-ordered phase. The fabricated capacitors exhibit excellent performance for memory applications, including low dielectric loss (<0.02 at 100 kHz), low leakage current (<10<sup>-7</sup> A/cm<sup>2</sup>), high operating speed (>20 MHz), and high endurance (>10<sup>10</sup> cycles). To validate practical utility, MoS<sub>2</sub> field-effect transistors gated by β-Ga<sub>2</sub>O<sub>3</sub> were fabricated, exhibiting a high on<i>/</i>off ratio (>10<sup>6</sup>), a low subthreshold swing (<i>SS</i>) of 68.1 mV/dec, negligible hysteresis (5.8 mV), and ultralow gate leakage (∼10<sup>-13</sup> A). These findings establish ultrathin β-Ga<sub>2</sub>O<sub>3</sub> as a compelling high-<i>k</i> material for next-generation logic and memory devices.