Abstract: Two-dimensional gallium nitride (GaN) exhibits broad application prospects in the field of ultraviolet optoelectronics due to its dual characteristics of wide-bandgap semiconductor and quantum confinement effect. However, conventional synthesis methods for 2D GaN, such as metal-organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE), typically require high growth temperatures, prolonged processing times, and relatively high costs. To address these critical challenges, this work leverages the intrinsic properties of liquid metal gallium, its low melting point and ease of oxidation to develop an efficient, relatively low-temperature synthesis strategy for 2D GaN. The core steps of this strategy include: First, utilizing a straightforward spin-coating exfoliation technique to directly extract an amorphous gallium oxide (Ga₂O₃) from the surface of liquid gallium. Subsequently, subjecting the amorphous Ga₂O₃ to a nitridation treatment process at a relatively low temperature of 850 ℃, successfully achieving its conversion into high-crystalline-quality GaN. Characterization results demonstrate that the synthesized 2D GaN possesses a thickness of approximately 2.2 nm, a lateral dimension on the centimeter scale, and a hexagonal wurtzite crystal structure. Our research group constructed a photoconductive ultraviolet photodetector based on the prepared two-dimensional GaN. Device performance characterization revealed that under a 5 V bias voltage and illumination by 325 nm UV light (with an intensity of 365 μW/cm²), the device exhibited a responsivity of 4.14 A/W and a high detectivity of 1.02 × 10¹³ Jones. This study demonstrates the successful preparation of large-area 2D GaN material based on liquid gallium metal, providing a valuable reference for the development of low-dimensional, high-performance UV photodetectors.

Key words: GaN, liquid metal gallium, spin-coating exfoliation method, ultraviolet photodetector