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Alloy engineering and heterostructures designing are two efficient methods to improve the photosensitivity of two-dimensional (2D) material-based photodetectors. Herein, we report the first-principle calculation about the band structure of SnS1-xSex (0 ≤ x ≤ 1) and synthesize these alloy nanosheets. Systematic measurements indicate that SnS0.25Se0.75 exhibits the highest hole mobility (0.77 cm2·V-1·s-1) and a moderate photoresponsivity (4.44 × 102 A·W-1) with fast response speed (32.1/57.5 ms) under 635 nm irradiation. Furthermore, to reduce the dark current and strengthen the light absorption, a self-driven SnS0.25Se0.75/n-Si device has been fabricated. The device achieved a preeminent photo-responsivity of 377 mA·W-1, a detectivity of ∼1011 Jones and Ilight/Idark ratio of ∼4.5 × 102. In addition, the corresponding rising/decay times are as short as 4.7/3.9 ms. Moreover, a broadband sensitivity from 635 to 1200 nm is obtained and the related photoswitching curves are stable and reproducibility. Noticeably, the above parameters are comparable or superior to the most of reported group IVA layered materials-based self-driven photodetectors. Last, the synergistic effects between the SnS0.25Se0.75 nanosheets and the n-Si have been discussed by the band alignment. These brilliant results will pave a new pathway for the development of next generation 2D alloy-based photoelectronic devices.

MoSe2/WSe2 two-dimensional transition-metal dichalcogenide (TMDC) heterojunction photodetectors based on epitaxial n-doped 4H-silicon carbide (SiC) substrate are investigated and exhibited low leakage, high stability, and fast photoresponse. The efficient separation of photogenerated carriers occurs between TMDCs and 4H-SiC, as indicated by the photoluminescence spectrum and the band alignment analysis under 532 nm. The MoSe2/WSe2/4H-SiC photodetector shows an obvious rectification behavior and unique current-gate voltage ( I- Vg) characteristics. The gate tunable photocurrent scanning maps display the highest photocurrent in the MoSe2/WSe2 region including a certain intensive current region in individual TMDCs/4H-SiC junctions under a 532 nm laser. Besides, the maximum responsivity of the heterojunction photodetectors is 7.17 A·W-1 with the Vg of 10 V at positive bias. The corresponding maximum external quantum efficiency and detectivity also significantly increase to 1.67 × 103% and 5.51 × 1011 jones with the largest Ilight/ Idark ratio of ∼103. Moreover, the MoSe2/4H-SiC photodetector delivers an enhanced photoresponse behavior with gate modulation, which is different from the previous paper. These results of our study demonstrate that MoSe2/WSe2 heterojunction photodetectors based on the n-doped 4H-SiC substrate will be a promising candidate for future optoelectronics applications in spectral responsivity.

Schottky-barrier field-effect transistors (SBFETs) based on multilayer WS2 with Au as drain/source contacts are fabricated in this paper. Interestingly, the novel polarity behavior of the WS2 SBFETs can be modulated by drain bias, ranging from p-type to ambipolar and finally to n-type conductivity, due to the transition of band structures and Schottky-barrier heights under different drain and gate biases. The electron mobility and the on/off ratio of electron current can reach as high as 23.4 cm2/(V s) and 8.5 × 107, respectively. Moreover, the WS2 SBFET possesses high-performance photosensitive characteristics with response time of 40 ms, photoresponsivity of 12.4 A/W, external quantum efficiency of 2420%, and photodetectivity as high as 9.28 × 1011 cm Hz1/2/W. In conclusion, the excellent performance of the WS2 SBFETs may pave the way for next-generation electronic and photoelectronic devices.

The emergence of a rich variety of layered materials has attracted considerable attention in recent years because of their exciting properties. However, the applications of layered materials in optoelectronic devices are hampered by the low light absorption of monolayers/few layers, the lack of p–n junction, and the challenges for large-scale production. Here, we report a scalable production of β-In2Se3/Si heterojunction arrays using pulsed-laser deposition. Photodetectors based on the as-produced heterojunction array are sensitive to a broadband wavelength from ultraviolet (370 nm) to near-infrared (808 nm), showing a high responsivity (5.9 A/W), a decent current on/off ratio (∼600), and a superior detectivity (4.9 × 1012 jones), simultaneously. These figures-of-merits are among the best values of the reported heterojunction-based photodetectors. In addition, these devices can further enable the detection of weak signals, as successfully demonstrated with weak light sources including a flashlight, lighte...

Because of their great potential for academic investigation and practical application in next-generation optoelectronic devices, ternary layered semiconductors have attracted considerable attention in recent years. Similar to the applications of traditional layered materials, practical applications of ternary layered semiconductor alloys require the synthesis of large-area samples. Here, we report the preparation of centimeter-scale and high-quality Mo0.5W0.5Se2 alloy films on both a rigid SiO2/Si substrate and a flexible polyimide (PI) substrate. Then, photodetectors based on these alloy films are fabricated, which are capable of conducting broad-band photodetection from ultraviolet to near-infrared region (370–808 nm) with high performance. The photodetector on SiO2/Si substrates demonstrates a high responsivity (R) of 77.1 A/W, an outstanding detectivity (D*) of 1.1 × 1012 Jones, and a fast response time of 8.3 ms. These figures-of-merit are much superior to those of the counterparts of binary material...

Layered materials have been found to be promising candidates for next-generation microelectronic and optoelectronic devices due to their unique electrical and optical properties. The p-n junction is an elementary building block for microelectronics and optoelectronics devices. Herein, using the pulsed-laser deposition (PLD) method, we achieve pure In2Se3-based photodetectors and In2Se3/CuInSe2-based photodetectors with a lateral p-n heterojunction. In comparison to that of the pure In2Se3-based photodetector, the photodetectors based on the In2Se3/CuInSe2 heterojunction exhibit a tremendous promotion of photodetection performance and obvious rectifying behavior. The photoresponsivity and external quantum efficiency of the fabricated heterojunction-based device under 532 nm light irradiation are 20.1 A/W and 4698%, respectively. These values are about 7.5 times higher than those of our fabricated pure In2Se3-based devices. We attribute this promotion of photodetection to the suitable band structures of In2Se3 and CuInSe2, which greatly promote the separation of photoexcited electron-hole pairs. This work suggests an effective way to form lateral p-n junctions, opening up a new scenario for designing and constructing high-performance optoelectronic devices.

Layered materials have rapidly established themselves as intriguing building blocks for next-generation photodetection platforms in view of their exotic electronic and optical attributes. However, both relatively low mobility and heavier electron effective mass limit layered materials for high-performance applications. Herein, we employed nanodiamonds (NDs) to promote the performance of multilayer In2Se3 photodetectors for the first time. This hybrid NDs-In2Se3 photodetector showed a tremendous promotion of photodetection performance in comparison to pristine In2Se3 ones. This hybrid devices exhibited remarkable detectivity (5.12 × 10(12) jones), fast response speed (less than 16.6 ms), and decent current on/off ratio (∼2285) simultaneously. These parameters are superior to most reported layered materials based photodetectors and even comparable to the state-of-the-art commercial photodetectors. Meanwhile, we attributed this excellent performance to the synergistic effect between NDs and the In2Se3. They can greatly enhance the broad spectrum absorption and promote the injection of photoexcited carrier in NDs to In2Se3. These results actually open up a new scenario for designing and fabricating innovative optoelectronic systems.