Wafer-scale synthesis of wide bandgap 2D GeSe2 layers for self-powered ultrasensitive UV photodetection and imaging

• Published in: Nano energy 2022-12, Vol.104, p.107972, Article 107972
• Main Authors: Wu, Di, Tian, Run, Lin, Pei, Shi, Zhifeng, Chen, Xu, Jia, Mochen, Tian, Yongtao, Li, Xinjian, Zeng, Longhui, Jie, Jiansheng
• Format: Article
• Language: English
• Subjects: GeSe2; Self-powered; Ultraviolet imaging; VdW heterojunction; Wide-bandgap 2D material
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2022.107972

Emerging wide-bandgap 2D GeSe2 has been considered as a promising candidate for next-generation ultraviolet (UV) imaging systems, which typically require miniaturization, high stability, and self-powered sensing capability. Nevertheless, the lack of reliable wafer-scale synthesis strategies remains a major obstacle to unleashing its full device potential. Herein, we report the synthesis of inch-level 2D GeSe2 layers with precise layer control and customized patterns via a facile post-annealing approach, which reveals a layer-independent direct bandgap of ∼3.0 eV. Moreover, high-quality GeSe2/GaN mixed-dimensional van der Waals heterojunctions fabricated via in-situ growth mode display an ultrasensitive self-powered UV photoresponse with a UV-to-visible rejection ratio of 1.8 × 105, a large responsivity of 261.7 mA/W, a high specific detectivity of 1.24 × 1014 Jones, as well as an ultrafast response speed to track nanosecond pulsed UV signals. In particular, the photodetector could sense ultraweak UV signals with a minimum detection limit of 180 pW/cm2 at 360 nm. Besides, the large-area growth of GeSe2 enables the implementation of integrated photodiode arrays for the self-powered image sensor, demonstrating the great promise of 2D GeSe2 for high-sensitivity UV detection and imaging. [Display omitted] •2-inch 2D GeSe2 layers with controllable layer numbers and patterns are synthesized.•A GeSe2/GaN vertical vdW heterojunction self-powered UV photodetector is in-situ fabricated.•The device shows a large D* of 1.24 × 1014 Jones and an ultrafast response speed.•The outstanding self-powered UV imaging applications are achieved.