Liquid-Metal-Assisted Growth of Vertical GaSe/MoS₂ p–n Heterojunctions for Sensitive Self-Driven Photodetectors

Abstract

van der Waals (vdW) vertical p−n junctions based on two-dimensional (2D) materials have shown great potential in flexible, self-driven, high-efficiency electronic and optoelectronic applications. However, due to the complex nucleation dynamics, the controllable synthesis of vertical heterostructures remains a daunting challenge. Here, we report the controlled growth of vertical GaSe/MoS 2 p−n heterojunctions via a liquid gallium (Ga)-assisted chemical vapor deposition method. The growth mechanism can be interpreted by theoretical calculations based on the Burton−Cabrera− Frank theory. By analyzing the diffusion barriers and the Ehrlich−Schwoebel barriers of adatoms, we found that the growth modes between vertical and lateral can be precisely switched by means of adjusting the amount of Ga. Based on the achieved high-quality vertical GaSe/MoS 2 p−n heterojunctions, photosensing devices are further designed and systematically investigated. Upon light illumination, prominent photovoltaic effects with large open-circuit voltage (0.61 V) and broadband detection capability from 375 to 633 nm are observed, which can further be employed for self-powered photodetection with high responsivity (900 mA/W) and fast response speed (5 ms). The developed liquid-metal-assisted strategy provides an effective method for controllable synthesis of vdW heterostructures and will give impetus to their applications in highperformance optoelectronic device.

Supported Cu/W/Mo/Ni—Liquid Metal Catalyst with Core-Shell Structure for Photocatalytic Degradation

“…The mechanism of liquid metal photocatalytic decomposition of organic pollutants is mainly caused by the Ga 2 O 3 semiconductor on its surface [33,34]. According to KK Z et al, gallium oxide has the advantage of providing photogenerated charge, and the bandgap was reported to be 4.2~4.9 eV [29].…”

Challenges and opportunities in 2D heterostructures for electronic and optoelectronic devices

“…Such VHS shows good photo conversion efficiency (4.5%) and fast photoresponse time (<500 μs) as compared to conventional TMDs based devices. HSs composed of transition metal mono- and di-chalcogenide-based GaSe/MoS 2 p-n vertical and lateral junctions were reported via liquid gallium-assisted two-step CVD method ( Zou et al., 2021 ). The growth direction of the GaSe layer was controlled by tuning the amount of Ga mixed with Ga 2 Se 3 powder on the as-grown 1L MoS 2 layer.…”

Advances in Self-Powered Ultraviolet Photodetectors Based on P-N Heterojunction Low-Dimensional Nanostructures

“…So far, researchers have made a lot of efforts and many gratifying developments have been acquired, but self-powered UV photodetectors with higher performance are still highly desired. On the one hand, exploring novel nanostructures that can promote the separation of photogenerated e-h pairs and be prepared by simple and stable methods may still be an important direction in the future; on the other hand, with the emergence of new high-performance semiconductor materials (such as graphdiyne [ 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 ], h-BN [ 112 , 113 , 114 , 115 , 116 ], perovskites [ 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 , 125 , 126 , 127 ], black phosphorus [ 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 ], and MoS 2 [ 136 , 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 ]), the situation of inorganic semiconductors as leading materials in self-powered photodetectors may be changed. In addition, inspired by the rise of wearable photodetectors in recent years, the new generation of photodetectors needs to be designed to be more dexterous and intelligent, which obviously puts forward new requir...…”