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Self‐powered near‐infrared (NIR) photodetectors utilizing low‐dimensional materials are promising owing to their low‐power‐consumption and superior photoresponse performance. The strong light‐matter interaction and other intriguing physical mechanisms (such as high mobility, dangling‐bond‐free surface) in 2D semiconductor materials, combined with the flexible fabrication of device structures, create new opportunities for the optoelectronic devices. Here, a self‐powered NIR Schottky junction photodetector is demonstrated by vertically stacking 2D PtSe2 film atop an InP wafer. The strong built‐in electric field formed at PtSe2/InP interface endows the device with self‐powered operation with an ultralow dark current of 45 pA at room temperature under 0 V bias. The responsivity and detectivity at 940 nm illumination reach up to 0.718 A W−1 and 4.37 × 1012 Jones, respectively. Furthermore, TCAD simulations showed that the significant electric field at the PtSe2/InP interface is pivotal for its superior self‐powered detection performance. Remarkably, the device achieves a high Ilight/Idark ratio exceeding 105 and a fast response time of 4.35/5.66 µs, and sensitivity to NIR light polarization. This study provides a new perspective for the integration of hybrid 2D materials with 3D semiconductors in the next‐generation optoelectronic devices and integrated systems. [ABSTRACT FROM AUTHOR]

Exploitation of low‐dimensional metal‐oxide semiconductor nanowires (MOS NWs) with peculiar and radial coaxial architectures is of great significance for constructing nanoscale, high‐performance, multi‐module integrable functional electronic products. Here, highly ordered In2O3@ZnO coaxial NW arrays (CNWA) using a simple and economical electrospinning technique are synthesized and assembled into field‐effect transistors (FETs). Featuring strong carrier effusion efficiency at the In2O3@ZnO circular heterogeneous interface, the field effect mobility (εFE) gets an intrinsic improvement and can reach as high as 202.3 cm2 V‒1 s‒1 for high‐k‐based CNWA FETs, which exceeds the performance of oxide‐based FETs devices reported by far. Furthermore, the unique structural advantages endowing In2O3@ZnO CNWA FETs with excellent optoelectronic coupling capabilities are identified, for which further optoelectronic detection and artificial photonic synaptic devices are constructed and functional simulations are implemented. This work offers new insights in designing optoelectronics and artificial synapses to process and recognize information for neuromorphic computing and artificial intelligence applications. [ABSTRACT FROM AUTHOR]

Accurate and quantifiable detection of the specific wavelength is vital in different application scenarios. Herein, a novel self‐driven narrowband photodetector (NB‐PD) based on CH(NH2)2PbBr2.5I0.5 crystal film is employed for building a yellow light intensity meter. By taking advantage of the carrier collection narrowing mechanism, a sensitive NB‐PD with peak response at 580 nm and the full‐width at half‐maximum of 23 nm are successfully achieved. The asymmetric contact electrodes of Ag/Pt allow the device to work without bias. The optoelectronic analysis demonstrates that the NB‐PD achieves a maximum responsivity of 59.89 mA W−1, a fast response speed of 202/331 µs, and a high on/off ratio of 636 at zero bias. Then, through introducing the back‐end circuit, a yellow light intensity meter is constructed with the NB‐PD. The absolute error and relative error of the light meter are estimated to be lower than 0.08 mW cm−2 and 4.22%, respectively, indicating the good capability for the yellow light monitoring. Given the simple device geometry and good performance, the achieved yellow light intensity meter can also be extended to other narrowband light detection system. [ABSTRACT FROM AUTHOR]

High‐precision spectral detection and broadband wavelength sensors have attracted considerable interest for important application in color image sensing. Due to the absorption limitations of silicon, conventional complementary metal–oxide–semiconductors have a relatively limited wavelength region from the ultraviolet to near‐infrared spectrum. Here, a simple‐structured device is developed by assembling two back‐to‐back monolayer graphene (MLG)/Si/MLG heterojunctions for high‐resolution wavelength sensing applications. The single MLG/Si/MLG photodetector exhibits a responsivity of 0.18 A W−1, a specific detectivity of 1.36 × 109 Jones, and an external quantum efficiency of 28.5%. Thanks to the unique device geometry, the distribution of photo‐generation rates in the two photodetectors is completely different, which brings about different photoelectric properties. It is found that the relationship between the photocurrent ratio of both photodetectors and the light wavelength can be fitted by a monotonic function, according to which the wavelength of incident light in the range from 260 to 1050 nm can be accurately estimated. A high resolution of 1 nm is demonstrated across a broadband wavelength from 260 to 1000 nm. This good resolution, along with good repeatability and stability, endow the present device with potential promise in future spectral sensing applications. [ABSTRACT FROM AUTHOR]

In this study, a solution method derived dual‐band photodetector (PD) based on silicon nanowires /PbS nanocrystalline film n–n heterojunction, which exhibits typical bias‐selectable spectral response in both near‐infrared (NIR) and short‐wave infrared (SWIR) bands, is presented. It is found that by adjusting the polarity of the bias voltage, the photoresponse of the device can be switched between three operation modes. The device exhibits high responsivities of 2100 mA W−1 at −0.15 V and 31 mA W−1 at 0 V, respectively, in the NIR region. Remarkably, the maximum responsivity and detectivity under 2000 nm illumination are determined as 290 mA W−1 and 2.4 × 1010 Jones, comparable to or even better than some PbS commercial PDs. The enhanced performance comes from the improved optical absorption and higher efficiency of charge separation and collection owing to the heterojunction geometry. It's also revealed that the bias‐controllable spectral response is attributed to the selectively transportation of photocarriers across the junction barrier. The study demonstrates the capability of detecting two distinct IR regions with the same pixel, which has great potential in future optoelectronic systems for IR imaging applications. [ABSTRACT FROM AUTHOR]

In this paper, a broadband wavelength sensor which is composed of two horizontally stacked photodetectors is reported. The top part is a monolayer graphene (MLG)/thin Si/MLG heterojunction device and the bottom part is a MLG/Ge Schottky junction device. Owing to the thin thickness of the Si and the wavelength‐dependent absorption coefficients of both Si and Ge, the two photodetectors exhibit sharp contrast in photon‐generation rate when illuminated with different wavelengths of light. This distinction in photon generation leads to completely different evolution in photocurrent, and the corresponding relationship between the photocurrent ratio and wavelength can be easily expressed as a monotonic function, via which the wavelength in a broad range from deep ultraviolet (265 nm) to near infrared light (1550 nm) can be easily calculated. Notably, the average relative error and the average absolute error of the wavelength sensor are estimated to be 2.1% and 2.3 nm, respectively, which are much better than previously reported values. [ABSTRACT FROM AUTHOR]

Self‐piercing riveting (SPR) has been used to joint steel to aluminum alloy sheets in multimaterial car body. It is a challenge to joint high strength steel to aluminum alloy by SPR process, especially for materials with high strength and large thickness. Herein, the SPR process for 1500 MPa hot stamped steel and aluminum alloy sheets is studied by experiment and simulation method. The laser heat treatment process is applied to the hot stamped steel sheet before joining. The relationship between heat treatment process and hardness distribution is studied and the softening zone with hardness less than 300 HV is obtained. Furthermore, the local softening zone is joined to an aluminum alloy sheet by SPR process. In the process, the rivets with high hardness are used to pierce the steel sheet. The failure mode and maximum tensile shear force of the joint are studied. At the same time, the joints without laser heat treatment are compared. The results show that the interlock and the maximum shear force for laser heat treatment increase by 91% and 26%, respectively. [ABSTRACT FROM AUTHOR]