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Van der Waals (vdW) heterostructures have gained significant attention in photodetectors due to their seamless integration with materials possessing diverse functionalities. In this study, the fabrication of a Te nanomesh/black‐Si vdW heterostructure is presented, and investigated its photoresponse properties. The heterostructure exhibits a pronounced rectification behavior, characterized by a rectification ratio of 2.2 × 104. Notably, the heterostructure device demonstrates commendable photoresponse properties, including a high responsivity of 350 mA W−1, an extensive linear dynamic range of 45.5 dB, a high specific detectivity of 9.6 × 1011 Jones, and a wide spectral response ranging from 400 to 1550 nm. Furthermore, the heterostructure exhibits rapid response, with a rise time and a decay time of 70 and 140 µs, respectively. These exceptional photoresponse properties can be attributed to the robust internal built‐in electrical field at the hetero‐interface and the augmented light absorption in black‐Si. The outstanding photoresponse properties of the heterostructure make it a promising candidate for multiwavelength single‐pixel imaging, enabling the collection of mask patterns under varying wavelengths of light radiation. This work provides a novel approach for fabricating mixed‐dimensional vdW heterostructures, offering promising prospects for advancements in optoelectronics. [ABSTRACT FROM AUTHOR]

PdSe2, a semiconductor with a narrow band gap, shows tremendous promise for high‐performance broadband photodetectors. In this study, highly sensitive, broadband, and flexible PdSe2 thin film photodetectors on polyimide (PI) substrates that can detect light from the UV (365 nm) to infrared (2200 nm) regions are reported. The devices with thick (21 nm) PdSe2 films show decent performance with a decent responsivity of 37.6 mA W−1 at 1550 nm and a fast response time. For the thick PdSe2 film, the bolometric effect dominates the positive photoresponse across all wavelength regions, whereas for the thin PdSe2 film (4.5–13 nm), which shows both positive and negative photoresponses, it dominates in the infrared region. The negative photoresponse of thin PdSe2 in the UV to the VIS region is attributed to the charge transfer‐related adsorption‐desorption of gas molecules. Detailed investigations revealed that the temperature coefficient of resistance (TCR) value is closely correlated to film thickness, with the thinnest film exhibiting the highest absolute TCR value of up to 4.3% °C−1. The value is much larger than that of metals, most 2D materials, amorphous Si, and even commercial VOx. These findings suggest that PdSe2 films have a promising future in broadband photodetectors. [ABSTRACT FROM AUTHOR]

Due to their excellent properties, ternary GaAsxSb1−x nanowires have been extensively investigated to enable various nanodevice structures. However, the surfactant effect of antimony has a notorious impact on the surface morphology and electrical properties of prepared Sb‐rich nanowires, restricting their practical utilization. Herein, through the in situ passivation effect of thiourea, highly‐crystalline, uniform, and thin GaAsxSb1−x nanowires (x ≤ 0.34) are successfully achieved. In contrast to low‐melting‐point sulfur powders typically used in surfactant‐assisted chemical vapor deposition, thiourea has a relatively higher melting point, facilitating the more controllable formation of SbxSy layer on the nanowire surface to minimize the radial growth and to stabilize the sidewalls for high‐quality Sb‐rich nanowires. When configured into field‐effect transistors, the obtained GaSb nanowires exhibit excellent device performance with a hole mobility of over 200 cm2 V−1 s−1. The optimal GaAs0.18Sb0.82 device yields an impressive responsivity of 5.4 × 104 A W−1 and an external quantum efficiency of 4.4 × 106% under near‐infrared light illumination. Importantly, the rise and decay times are as efficient as 80 and 104 µs, respectively, which are better than any values reported for GaAsSb nanowire photoconductors to date. All these results demonstrate the promising potential of GaAsxSb1−x nanowires for high‐mobility electronics and ultrafast near‐infrared optoelectronics. [ABSTRACT FROM AUTHOR]

Due to excellent electrical and optoelectronic properties, 2D transition metal dichalcogenides and their van der Waals (vdW) heterostructures have attracted great attention for broadband optoelectronics. Here, an unreported vdW PdSe2/WS2 heterostructure is developed for robust high‐performance broadband photodetection from visible to infrared optical communication band. These heterostructure devices are simply formed by direct selenization of Pd films pre‐deposited on the chemical vapor deposited monolayer WS2, followed by wet‐transfer onto device substrates with pre‐patterned electrodes. Importantly, the obtained heterostructure device exhibits an impressive broadband spectral photoresponse with response times less than 100 ms for different wavelength regions (532 to 1550 nm), where this performance is significantly better than that of pristine monolayer WS2 devices. This performance enhancement is attributed to the type I band alignment of the heterostructure. Under illumination, both intralayer and interlayer excitations are involved to generate carriers in the relevant layer, enabling the broadband photoresponse. Photocarriers would then undergo charge separation in the depletion region with electrons transferred into the charge transport layer of WS2 through the built‐in electric field, followed by the relaxation to valance band via interlayer or intralayer transition. All these findings can indicate the promising potential of vdW PdSe2/WS2 heterostructures for next‐generation high‐performance optoelectronics. [ABSTRACT FROM AUTHOR]