Few-Layer MoS₂ with High Broadband Photogain and Fast Optical Switching for Use in Harsh Environments

Abstract

Few-layered MoS2 as Schottky metal-semiconductor-metal photodetectors (MSM PDs) for use in harsh environments makes its debut as two-dimensional (2D) optoelectronics with high broadband gain (up to 13.3), high detectivity (up to ~10(10) cm Hz(1/2)/W), fast photoresponse (rise time of ~70 μs and fall time of ~110 μs), and high thermal stability (at a working temperature of up to 200 °C). Ultrahigh responsivity (0.57 A/W) of few-layer MoS2 at 532 nm is due to the high optical absorption (~10% despite being less than 2 nm in thickness) and a high photogain, which sets up a new record that was not achievable in 2D nanomaterials previously. This study opens avenues to develop 2D nanomaterial-based optoelectronics for harsh environments in imaging techniques and light-wave communications as well as in future memory storage and optoelectronic circuits.

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.…”

“…Among various 2D materials, MoS 2 has shown excellent properties in optoelectronic applications due to its suitable band gap value,5, 6 relatively high carrier mobility,2, 7 high light absorbance,3, 8 and, more importantly, good stability,9, 10 and brilliant optoelectronic properties 1, 7, 11, 12. However, pure MoS 2 ‐based optoelectronic devices are usually limited to infrared light detection and lower photoelectric conversion efficiency (PCE) because of the direct band gap of 1.8 eV for single‐layered MoS 2 sheet5, 6 and the picosecond ultrashort carrier lifetime 13, 14.…”

Monolayer MoS 2 /GaAs heterostructure self-driven photodetector with extremely high detectivity

“…Moreover, piezoelectric properties of MoS 2 allow multi-functional photodetector device design [29]. However, the absence of high-quality p-n junctions makes 2D MoS 2 -based photodetectors suffering from low detectivity (10 8 -10 10 Jones) (Jones = cm Hz 1/2 W −1 ) and slow response speed (70-10 6 μs) [30][31][32]. The thinnest MoS 2 /graphene and WS 2 /MoS 2 stacked heterostructure shows a power conversion efficiencies of less than 1% as very small part of light can be absorbed [33,34].…”

Ultrafast, Broadband Photodetector Based on MoSe2/Silicon Heterojunction with Vertically Standing Layered Structure Using Graphene as Transparent Electrode

“…Significantly, the Gr/MoSe 2 /Si heterojunction photodetector exhibited a wide photoresponse range of 350–1310 nm and an extremely fast response speed of ≈270 ns, which represent the best values reported thus far for MoSe 2 or MoS 2 based photodetectors ( Table 1 ). 43, 44, 45, 51, 52, 53, 54 It is expected that the MoSe 2 /Si heterojunctions will have important applications for high‐performance optoelectronic devices.…”