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Nanostructured films have been widely used for preparing various advanced thin-film devices because of their unique electrical, optical, and plasmonic characteristics associated with the nano-size effect. In situ, nondestructive and high-resolution characterization of nanostructured films is essential for optimizing thin-film device performance. In this work, such thin-film characterization was achieved using a hyperspectral dark-field microscope (HSDFM) that was constructed in our laboratory by integrating a hyperspectral imager with a commercial microscope. The HSDFM allows for high-resolution (Δλ = 0.4 nm) spectral analysis of nanostructured samples in the visible-near-infrared region with a spatial resolution as high as 45 nm × 45 nm (corresponding to a single pixel). Four typical samples were investigated with the HSDFM, including the gold nanoplate array, the self-assembled gold nanoparticle (GNP) sub-monolayer, the sol-gel nanoporous titanium dioxide (TiO2) film, and the layer-stacked molybdenum disulfide (MoS2) sheet. According to the experimental results, the plasmon resonance scattering bands for nanoplate clusters are identical with those for individual gold nanoplates, indicating that the gap between adjacent nanoplates is too large to allow plasmonic coupling between them. A different case was observed with the self-assembled GNP sub-monolayer in which the aggregated clusters with the internal plasmonic interaction show a considerable red-shift of the plasmon resonance band relative to the isolated single GNP. In addition, the protein adsorption on the nanoporous TiO2 film was observed to be inhomogeneous on the microscale, and the stepped boundaries of the MoS2 sheet were clearly observed. A quasi-linear dependence of the single-pixel light intensity on the step height was obtained by combining the HSDFM with atomic force microscopy. The minimum thickness detectable by the present HSDFM is 6.5 nm, corresponding to the 10-layer MoS2 film. The work demonstrated the outstanding applicability of the HSDFM for nanostructured film characterization.

Gallium nitride (GaN) field-effect transistors have low ON resistance and switching losses in high-frequency (>MHz) resonant wireless power transfer systems. Nevertheless, their performance in the system is determined by their characteristics and operation mode. A particular operating mode in a 6.78-MHz magnetic resonant wireless transfer system that employs class-D GaN power amplifiers in the zero-voltage switching mode is studied. Two operation modes, the forward mode and the reverse mode, are investigated. The nonideal effect under the device-level dynamic resistance and thermal effect are also analyzed. The dynamic resistance under different operation modes is demonstrated to have different generation mechanisms. Finally, the device characteristics with system operating conditions are combined, and the effects of temperature and dynamic resistance under different operating conditions are evaluated.

Optical metasurfaces provide a significant approach for the production of structural colors due to their excellent optical control abilities. Herein, we propose trapezoidal structural metasurfaces for achieving multiplex grating-type structural colors with high comprehensive performance originating from the anomalous reflection dispersion in the visible band. Single trapezoidal metasurfaces with different x-direction periods can tune the angular dispersion regularly from 0.036 rad/nm to 0.224 rad/nm to generate various structural colors, and composite trapezoidal metasurfaces with three kinds of combinations can achieve multiplex sets of structural colors. The brightness can be controlled by adjusting the distance between the trapezoids in a pair accurately. The designed structural colors have higher saturation than traditional pigmentary colors, whose excitation purity can reach 1.00. The gamut is about 158.1% of the Adobe RGB standard. This research has application potential in ultrafine displays, information encryption, optical storage, and anti-counterfeit tagging.

This paper proposes a metasurface based on H-fractal unit structure, which exhibits three transmission resonance peaks. The simulation results show that these peaks are very sensitive to samples with different refractive indexes. The biggest frequency shift of these resonant peaks is about 2.6 GHz when the refractive index of samples changes by 1 and the quality factor(Q) values of the second and the third peak are up to 191.55 and 179.40 respectively, which has great application potential in the field of microwave sensing because its high-sensitivity and high-Q.

The chemical reaction between acid and rock mineral during the acidizing process is the key point for the acidizing technique. In this study a rotating disk method is used to simulate strata conditions, such as high temperature, high pressure, and acid shear flow reaction. The work investigates the kinetics of the rock acidizing reaction and analyzes the factors effecting the reaction rate, including mineral composition, temperature, pressure, acid concentration, shear velocity, and common-ion effect. The kinetic parameters, such as velocity constant, reaction order, activation energy, and frequency factor, were successfully extracted by curve fitting and the linear regression method. In was shown that hydrochloric acid does not participate directly in the reaction between mud acid (which is a mixture of hydrochloric and hydrofluoric acids) and sandstone mineral but catalyzes the reaction between hydrofluoric acid and sandstone. In this work, the acid rock reaction rate equation has been established, and the impact of the hydrochloric acid catalytic effect has been considered.

Based on a self-terminating gate recess etching technique, we successfully fabricated a high-breakdown-voltage and high-threshold-voltage normally-off SiN/AlN/GaN-on-Si metal-insulator-semiconductor-field-effect-transistor (MIS-FET) with optimized PEALD-AlN (plasma-enhance-atomic-layer-deposition) protection layer and in situ NH3 pre-treatment. Compared with thermal-ALD-AlN, the PEALD-AlN protection layer could form a lower interface state density with the GaN channel. Moreover, the in situ NH3 pre-treatment performed in the PEALD system prior to PEALD-AlN deposition could further improve the interface quality. Using in situ NH3 pre-treatment and a PEALD-AlN protection layer, the fabricated SiN/AlN/GaN-on-Si MIS-FET exhibits a high-threshold-voltage of 2.60 V at I D of 1 μA mm−1 (6.57 V by linear extrapolation) and a high-breakdown-voltage of 1775 V.

In this work, we report a novel surface-enhanced Raman scattering (SERS) substrate based on nanostructured diamond. Hemispheric nanocrystalline diamond grown by MPCVD was annealed in air to achieve hemispheric NCD with nano-thorn-like porous structure (HSDNT). Subsequently, thin Au film was coated onto the HSDNT surface by evaporation. The large specific surface area and “lightning rod” effect provided by HSDNT greatly improved the SERS effect. Detection limit low to 10−12 M and even 10−14 M after ultrasonic process was obtained experimentally on Au-HSDNT for the first time.

This paper reports an integrated bifunctional metasurface composed of metal-dielectric-metal (MDM) trapezoidal nanoantennas. Polarization, wavelength, and angle are all multiplexed to improve the integration and the performance of the metasurface. Under orthogonal-polarized incidence, phase and amplitude are tuned independently by gap surface plasmon (GSP) resonance, leading to the combination of beam deflection and structural color printing functions. Both functions work in broadband, namely, 360 nm to 540 nm for beam deflection function and 400 nm to 800 nm for structural color printing function. Angle multiplexing further improves the tunability of the two functions. This integrated bifunctional metasurface is very suitable to be used in ultra-compact optics systems, and may find more applications in optical and biological sensing areas.

Computational prediction of inhibition efficiency (IE) for inhibitor molecules is a crucial supplementary way to design novel molecules that can efficiently inhibit corrosion onto metallic surfaces. Here we are dedicated to developing a new machine learning-based predictor for the inhibition efficiency (IE) of benzimidazole derivatives. First, a comprehensively numerical representation was given on inhibitor molecules from all aspects of energy, electronic, topological, physicochemical and spatial properties based on 3-D structures and 150 valid structural descriptors were obtained. Then, a thorough investigation of these structural descriptors was implemented. The multicollinearity-based clustering analysis was performed to remove the linear correlated feature variables, so 47 feature clusters were produced. Meanwhile, Gini importance by random forest (RF) was used to further measure the contributions of the descriptors in each cluster and 47 non-linear descriptors were selected with the highest Gini importance score in the corresponding cluster. Further, considering the limited number of available inhibitors, different feature subsets were constructed according to the Gini importance score ranking list of 47 descriptors. Finally, support vector machine (SVM) models based on different feature subsets were tested by leave-one-out cross validation. Through comparisons, the optimal SVM model with the top 11 descriptors was achieved based on Poly kernel. This model yields a promising performance with the correlation coefficient (R) and root-mean-square error (RMSE) of 0.9589 and 4.45, respectively, which indicates that the method proposed by us gives the best performance for the current data. Based on our model, 6 new benzimidazole molecules were designed and their IE values predicted by this model indicate that two of them have high potential as outstanding corrosion inhibitors.

Amplitude based coupled dual-microcantilevers have showed great sensitivity improvement compared with traditionally investigated frequency-shift based single cantilever which is meaningful for highly sensitive bio/chemical detection. In this paper, weaker coupling structures and less mass difference between the two coupled cantilevers were found to contribute to a better minus mass detection sensitivity. Emergence of the coupled states for coupled dual-microcantilevers under piezo-actuation was discovered to be easier with smaller damping force, stronger coupling effect and greater mass difference between the two coupled beams. Besides, the amplitude-ratio was found to be a more significant sensing factor for suppressing the actuating contributed noise compared to traditional amplitude index.