The formation of semiconductor heterostructures is an effective approach to achieve high performance in electrical gas sensing. However, such heterostructures are usually prepared via multi‐step procedures. In this contribution, by taking advantage of the crystal phase‐dependent electronic property of SnSex based materials, we report a one‐step colloid method for the preparation of SnSe(x%)/SnSe2(100−x%) p–n heterostructures, with x ≈30, 50, and 70. The obtained materials with solution processability were successfully fabricated into NO2 sensors. Among them, the SnSe(50 %)/SnSe2(50 %) based sensor with an active layer thickness of 2 μm exhibited the highest sensitivity to NO2 (30 % at 0.1 ppm) with a limit of detection (LOD) down to 69 ppb at room temperature (25 °C). This was mainly attributed to the formation of p–n junctions that allowed for gas‐induced modification of the junction barriers. Under 405 nm laser illumination, the sensor performance was further enhanced, exhibiting a 3.5 times increased response toward 0.1 ppm NO2, along with a recovery time of 4.6 min.

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Abstract2D van der Waals (vdW) transition metal di‐chalcogenides (TMDs) have garnered significant attention in the nonvolatile memory field for their tunable electrical properties, scalability, and potential for phase engineering. However, their complex switching mechanism and complicated fabrication methods pose challenges for mass production. Sputtering is a promising technique for large‐area 2D vdW TMD fabrication, but the high melting point (typically Tm > 1000 °C) of TMDs requires elevated temperatures for good crystallinity. This study focuses on the low‐Tm 2D vdW TM tetra‐chalcogenides and identifies NbTe4 as a promising candidate with an ultra‐low Tm of around 447 °C (onset temperature). As‐grown NbTe4 forms an amorphous phase upon deposition that can be crystallized by annealing at temperatures above 272 °C. The simultaneous presence of a low Tm and a high crystallization temperature Tc can resolve important issues facing current phase‐change memory compounds, such as high Reset energies and poor thermal stability of the amorphous phase. Therefore, NbTe4 holds great promise as a potential solution to these issues.

This paper describes a novel method for digitizing the 3D shape of an object in real-time, which can be used for capturing live sequence of the 3D shape of moving or deformable objects such as faces. Two DMD (=Digital Micro Mirror) devices are used as high speed switches for modulating and demodulating light rays. One DMD is used to generate rays of light pulses, which are projected onto the object to be measured. Another DMD is used to demodulate the light reflected from the object illuminated by the light pulses into intensity image that describes the disparity. A prototype range finder implementing the proposed method has been built. The experimental results showed that the proposed method works and video sequences of disparity images can be captured in real time.

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† Cheng Li, Bin Fang and Like Zhang contributed equally to this work. nanoseconds, which cannot support applications in the ter-44 ahertz field. To tackle this issue, the approach of applying 45 a femtosecond laser pulse in a specifically designed mag-46 netic heterostructure [18] is proposed, which reduces the 47 timescale of spin-electricity conversion to the subpicosec-48 ond range, enabling the engineering of terahertz spintronic 49 devices. Therefore, this holds out the promise of spin-50 tronic terahertz emitters. In this respect, emerging terahertz 51 devices comprised of a variety of nonmagnetic materials 52 or interfaces, such as heavy metal [19-24], topological 53 insulator [25-28], and Ag/Bi Rashba interface [29,30], 54 have been validated. Apart from that, by using the afore-55 mentioned spin-to-charge conversion of antiferromagnetic 56 materials, Chen et al. proposed a compensated magnetic 57 heterostructure consisting of ferrimagnet and antiferro-58 magnet to operate as a terahertz emitter [31]. Mean-59 while, Zhou et al. observed terahertz emission in a non-60 collinear antiferromagnetic Mn 3 Sn heterostructure [32], 61 which extends the material selection for spintronic tera-62 hertz emitters. Nevertheless, neither detailed experimental 63 analysis nor quantitative calculation is explicitly presented 64 2331-7019/21/0(0)/XXXXXX(7) XXXXXX-1

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