High-Responsivity Photovoltaic Photodetectors Based on MoTe2/MoSe2 van der Waals Heterojunctions

Abstract

Van der Waals heterojunctions based on transition metal dichalcogenides (TMDs) show promising potential in optoelectronic devices, due to the ultrafast separation of photoexcited carriers and efficient generation of the photocurrent. Herein, this study demonstrated a high-responsivity photovoltaic photodetector based on a MoTe2/MoSe2 type-II heterojunction. Due to the interlayer built-in potential, the MoTe2/MoSe2 heterojunction shows obvious photovoltaic behavior and its photoresponse can be tuned by the gate voltage due to the ultrathin thickness of the heterojunction. This self-powered photovoltaic photodetector exhibits an excellent responsivity of 1.5 A W−1, larger than previously reported TMDs-based photovoltaic photodetectors. Due to the high-efficiency separation of electron-hole pairs and ultrafast charge transfer, the light-induced on/off ratio of current switching is larger than 104 at zero bias, and the dark current is extremely low (~10−13 A). These MoTe2/MoSe2 type-II heterojunctions are expected to provide more opportunities for future nanoscale optoelectronic devices.

A comparative study of electrical and opto-electrical properties of a few-layer p-WSe2/n-WS2 heterojunction diode on SiO2 and h-BN substrates

“…These values we obtained in device2 are far better than the values reported before with the identical conditions in TMD heterostructures. [28][29][30]58,59 The higher values of R and EQE in our device2 is mainly attributed to the use of h-BN substrate, which enhances the photo absorption and the photocurrent due to the lower trap states, 59,60 as well as the excellent photo response of WSe 2 (ref. [61][62][63] and WS 2 (ref.…”

“…The observed increase of R as P decreases is in consistence with the articles published before. 30,57,58 R is about 3.0 A W À1 and 1.6 A W À1 with power density of 10 mW cm À2 for device2 and device1, respectively. The EQE is dened as the number of photo-generated carriers where h is the Planck's constant, c the speed of light, and e the elementary charge.…”

“…In addition, a fast photo-carrier separation and the resulting short transit time due to the large built-in potential may contribute to a signicant gain and the large EQE. 58,64,65…”

Recent Progress in Two-Dimensional MoTe2 Hetero-Phase Homojunctions

“…As is mentioned above, few-layer 2H-MoTe 2 possesses an indirect bandgap of 0.8 eV, which is suitable for near-infrared (NIR) photodetection [ 78 ]. The photogating effect was considered to dominate the photocurrent generation in few-layer 2H-MoTe 2 -based photodetectors and the detailed mechanism was demonstrated as follows: after the generation of electron–hole pairs under irradiation, the charged trap states in the channel acted as a local floating gate and induced more electrons by trapping holes, leading to effective tuning of the channel conductance [ 79 , 80 ].…”

Recent progress about 2D metal dichalcogenides: Synthesis and application in photodetectors

“…Up to now, photodetectors based on 2D MDCs and their heterostructures have shown enhanced performances such as fast response speed [53][54][55][56][57][58], high responsivity [59][60][61][62][63] and high detectivity [64][65][66][67]. The schematic of the MDCs and their heterostructures used for photodetectors is illustrated in Fig.…”