Laminated deposition enabled two-dimensional bismuth antimony diodes with a cut-off frequency of ∼50 GHz.

Authors

Chengdong Zhao, Shuo Wang, Xing Yu, Yuxi Ji, Xuyan Zhang, Zhehan Wang, Jinlan Wang, Yichen Liu, Li Tao

Published in

Nanoscale. Jul 22, 2026. Epub Jul 22, 2026.

Abstract

As a prototypical topological insulator, the bismuth-antimony (Bi_1-xSb_x) alloy offers both a large spin Hall angle and high carrier mobility. However, preserving their surface-dominated transport properties in the quasi-two-dimensional (quasi-2D) limit remains challenging due to carrier scattering induced by surface roughness. Here, we report a laminated growth strategy followed by a self-diffusion process that enables the fabrication of high-quality quasi-2D Bi_1-xSb_x films with precisely controlled compositions, smooth surfaces, and the preferred (00l) orientation. The effective mass of Bi_1-xSb_x can be effectively manipulated by controlling the Sb content. Notably, the surface roughness of the Bi_0.5Sb_0.5 film (∼0.2 nm) is substantially lower than that of pure Bi (∼7.6 nm) and pure Sb (∼6.3 nm), indicating effective suppression of surface scattering. As a result, the 2D Bi_0.5Sb_0.5 films exhibit a high room-temperature electron mobility of up to 1500 cm² V^-1 s^-1. The optimized surface quality also yields a 20-fold enhancement in mobility relative to previous BiSb films of similar thicknesses. Furthermore, Ti/Bi_0.5Sb_0.5/Pt Schottky diodes fabricated from these films demonstrate a cut-off frequency of 48 GHz, underscoring their potential for high-frequency rectification and advanced 6G communication applications.

PMID:
42484915
Bibliographic data and abstract were imported from PubMed on 22 Jul 2026.

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