Liquid metal-based printing synthesis of bismuth-doped gallium oxide and its application for a photodetector

Two-dimensional gallium oxide (Ga₂O₃) is a promising material with diverse applications, but its development and application are hindered by the complicated synthesis process of 2D Ga₂O₃ film. However, the van der Waals printing method, which employs liquid metal as a platform, can simply synthesize large-scale and high-quality 2D oxide films with ease. Moreover, the band structure of oxide films can be modulated through doping during the printing process, broadening their applications. In this study, pure and doped Ga₂O₃ films have been successfully synthesized by using Bi-Ga alloys with different ratios (0 wt% Bi, 1 wt% Bi, 10 wt% Bi, 15 wt% Bi) via the van der Waals printing method. Furthermore, the modulation of the band structure of Ga₂O₃ films by doping ranging from 5.23 eV to 4.88 eV is systematically investigated. Photodetectors based on Ga₂O₃ films with a controllable band structure have been fabricated, which demonstrated good sensing performance with a responsivity of 959 mA W⁻¹, detectivity of 3.43 × 10¹¹ Jones, and response/recovery time of 13 ms/18 ms. This printing method provides a straightforward, low-cost, and high-efficiency strategy for synthesizing and doping 2D oxide films, which could advance their practical applications.