In Situ Fabrication of Vertical Multilayered MoS₂/Si Homotype Heterojunction for High-Speed Visible-Near-Infrared Photodetectors

Abstract

c2D transition metal dichalcogenides (TMDCs)-based heterostructures have been demonstrated to achieve superior light absorption and photovoltaic effects theoretically and experimentally, making them extremely attractive for realizing optoelectronic devices. In this work, a vertical multilayered n-MoS2/n-silicon homotype heterojunction is fabricated, which takes advantage of multilayered MoS2 grown in situ directly on plane silicon. Electrical characterization reveals that the resultant device exhibits high sensitivity to visible-near-infrared light with responsivity up to 11.9 A W(-1). Notably, the photodetector shows high-speed response time of ≈ 30.5 µs/71.6 µs and capability to work under higher pulsed light irradiation approaching 100 kHz. The high response speed could be attributed to a good quality of the multilayer MoS2 , as well as in situ device fabrication process. These findings suggest that the multilayered MoS2 /Si homotype heterojunction have great potential application in the field of visible-near-infrared detection and might be used as elements for construction of high-speed integrated optoelectronic sensor circuitry.

Ultrahigh, Ultrafast, and Self‐Powered Visible‐Near‐Infrared Optical Position‐Sensitive Detector Based on a CVD‐Prepared Vertically Standing Few‐Layer MoS2/Si Heterojunction

“…In addition, the lateral photovoltage balance values remain nearly constant for each laser power without depending on the chopper frequency, and V max increases gradually until becoming saturated with increasing laser power, as shown in Figure 4f, which is consistent with the LPE results. More importantly, it is noteworthy that the response time of this heterojunction is much faster than those of most reported MoS 2 ‐based photodetectors 10, 11, 12, 30, 59, 60, 61, 62, 63. Though ultrafast and stable photoresponse with no degradation, as well as resistance capacitance (RC)‐limited bandwidth, of the optoelectric devices is one of the basic requirements for applications in high‐speed optical communications, until now, the frequency of the modulated laser has been lower than 4000 Hz in most of the previously reported nano‐PDs, which will hinder their application in dynamic real‐time detection of the optical signal.…”

“…Then, the response speed, which is another key figure of merit for an optical photodetector,30, 33, 49 is investigated in detail in the V‐MoS 2 /Si heterojunction. Generally, the response speed of a PSD should be higher than the fastest temporal variation in the signal and should have a frequency response that has a bandwidth covering the entire bandwidth of the signal to get a faithful optical signal.…”

“…Additionally, monolayer or few‐layer MoS 2 can only absorb a small portion of incident light due to its ultrathin thickness, and its excellent optical absorption property cannot be well developed, thus restricting photocurrent (/photovoltage) improvement in MoS 2 ‐based devices. Therefore, recently, researchers have tried to prepare large‐scale uniform multilayer27 or bulk MoS 2 28 and have conceived a feasible and easy way to construct high‐performance optoelectronic devices by combining a 2D layered material with a traditional Si semiconductor,29, 30, 31, 32 as Si still dominates the commercial photovoltaic or optoelectronic market due to high abundance, acceptable power conversion efficiencies, and mature semiconductor technologies. Although the optical absorption can be improved greatly, the existing numerous defects result in serious recombination, and good PCEs still cannot be obtained 31, 32.…”

Hybrid Perovskite Photoconductivity Visible Region Detector with High Speed and Stability

“…The characteristic response time is also a critical parameter for the PDs, which re°ects the sensitivity of the device to the incident light, ensuring the devices can signi¯cantly follow a varied optical signal. 26 As illustrated in Fig. 4(a), the response …”

Recent Advances in van der Waals Heterojunctions Based on Semiconducting Transition Metal Dichalcogenides

“…Reproduced with permission [163]. a) Schematic of device structure based on the multilayered n-MoS 2 /n-Si heterojunction.…”