Wafer-scale heterogeneous integration InP on trenched Si with a bubble-free interface

Heterogeneous integration of compound semiconductors on a Si platform leads to advanced device applications in the field of Si photonics and high frequency electronics. However, the unavoidable bubbles formed at the bonding interface are detrimental for achieving a high yield of dissimilar semiconductor integration by the direct wafer bonding technology. In this work, lateral outgassing surface trenches (LOTs) are introduced to efficiently inhibit the bubbles. It is found that the chemical reactions in InP-Si bonding are similar to those in Si-Si bonding, and the generated gas can escape via the LOTs. The outgassing efficiency is dominated by LOTs\u27 spacing, and moreover, the relationship between bubble formation and the LOT\u27s structure is well described by a thermodynamic model. With the method explored in this work, a 2-in. bubble-free crystalline InP thin film integrated on the Si substrate with LOTs is obtained by the ion-slicing and wafer bonding technology. The quantum well active region grown on this Si-based InP film shows a superior photoemission efficiency, and it is found to be 65% as compared to its bulk counterpart

Large room-temperature magnetoresistance in van der Waals ferromagnet/semiconductor junctions

The magnetic tunnel junction (MTJ) is the core component in memory technologies, such as the magnetic random-access memory, magnetic sensors and programmable logic devices. In particular, MTJs based on two-dimensional (2D) van der Waals (vdW) heterostructures offer unprecedented opportunities for low power consumption and miniaturization of spintronic devices. However, their operation at room temperature remains a challenge. Here, we report a large tunnel magnetoresistance (TMR) of up to 85% at room temperature (T = 300 K) in vdW MTJs based on a thin (< 10 nm) semiconductor spacer WSe2 layer embedded between two Fe3GaTe2 electrodes with intrinsic above-room-temperature ferromagnetism. The TMR in the MTJ increases with decreasing temperature up to 164% at T = 10 K. The demonstration of TMR in ultra-thin MTJs at room-temperature opens a realistic and promising route for next-generation spintronic applications beyond the current state of the art

Position Control Study on Pump-Controlled Servomotor for Steam Control Valve

In steam turbine control and actuation, the steam control valve plays a key role in operability and reliability. The electrohydraulic regulating system for the steam control valve, usually called the servomotor, needs to be reliable and high performing under nonlinear excitation interference in actual conditions. Currently, electrohydraulic servo valve control technology is widely used in servomotors. Although this technology has good control performance, it still has some technical defects, such as poor antipollution ability, low energy efficiency, large volume size, and limited installation space. Aiming at the abovementioned technical shortcomings of electrohydraulic servo valve control technology, a servomotor-pump-hydraulic cylinder volume control scheme is proposed in this paper, forming a pump-controlled servomotor for the steam control valve. By analyzing the working principle of the pump-controlled servomotor position control in the steam control valve, the mathematical model of a pump-controlled servomotor for the steam control valve is established. The sliding mode variable structure control strategy is proposed, and the variable structure control law is solved by constructing a switching function. To verify the performance of the proposed control method, experimental research was conducted. The research results show that the proposed sliding mode variable structure control strategy has a good control effect, which lays the theoretical and technical foundation for the engineering application and promotion of pump-controlled servomotors for steam control valves and helps the technical upgrade and product optimization of steam turbines

Antibacterial Activity of Oxygen Vacancy-Mediated ROS Production of V₆O₁₃ Powder against <i>Candida albicans</i>

The emergence of drug resistance due to the overuse of antibiotics has made the prevention and treatment of invasive fungal infections caused by Candida albicans (C. albicans) a great challenge. Oxygen vacancy-rich inorganic materials show great promise in the antimicrobial field due to their unique physicochemical properties. Defect engineering can significantly optimize the electronic structure of inorganic materials to further enhance their antimicrobial activity. We designed oxygen vacancy defect-rich V6O13 powders using the hydrothermal-calcination method and investigated their anti-C. albicans activity. The results showed that the stronger antibacterial activity is attributed to the fact that the optimized V6O13 powder oxygen vacancy defects induced a reduction reaction of dissolved oxygen in the environment, which produced ROS with strong oxidative properties, causing damage to the wall membrane of C. albicans and leakage of intracellular material. The minimum inhibitory concentration (99% or more inhibition) of V6O13 powders is 4 mg/mL. This work not only provides a facile method for constructing oxygen-rich vacancies in V6O13 powders, but also provides new insights into the potential of inorganic materials optimized by defect engineering for efficient antimicrobial activity

Significantly Enhanced Self-Cleaning Capability in Anatase TiO₂ for the Bleaching of Organic Dyes and Glazes

In this study, the Mg2+-doped anatase TiO2 phase was synthesized via the solvothermal method by changing the ratio of deionized water and absolute ethanol Vwater/Vethanol). This enhances the bleaching efficiency under visible light. The crystal structure, morphology, and photocatalytic properties of Mg-doped TiO2 were characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, N2 adsorption-desorption, UV-Vis spectroscopy analysis, etc. Results showed that the photocatalytic activity of the Mg2+-doped TiO2 sample was effectively improved, and the morphology, specific surface area, and porosity of TiO2 could be controlled by Vwater/Vethanol. Compared with the Mg-undoped TiO2 sample, Mg-doped TiO2 samples have higher photocatalytic properties due to pure anatase phase formation. The Mg-doped TiO2 sample was synthesized at Vwater/Vethanol of 12.5:2.5, which has the highest bleaching rate of 99.5% for the rhodamine B dye during 80 min under visible light. Adding Mg2+-doped TiO2 into the phase-separated glaze is an essential factor for enhancing the self-cleaning capability. The glaze samples fired at 1180 °C achieved a water contact angle of 5.623° at room temperature and had high stain resistance (the blot floats as a whole after meeting the water)

Preparation of Glass-Ceramics in the R₂O-Bi₂O₃-B₂O₃-SiO₂ System Applied in Automobile Glass Enamel

Environmental deterioration has put higher requirements on the acid resistance of automotive glass enamel. The present paper aims to prepare acid-resistant glass-ceramics used in automobile glass enamel. Base glasses with the compositions 15R2O-xBi2O3-10B2O3-(75-x) SiO2 (R2O is a mixture of Li2O, Na2O, and K2O (1:1:1, molar ratio), where x = 10, 15, 20, 25, and 30, respectively) was prepared by the melt-quenching method, and glass-ceramics were prepared by their controlling crystallization heat treatment. Crystallization behavior and crystallization ability of base glasses were investigated using the thermal stability parameter (S), the crystallization kinetics calculation results of base glasses, as well as the phase identification results of the heat-treated samples. The effects of the heat treatment temperature on the micromorphology and acid resistance of the heat-treated glasses were also investigated. Then, the optimized glass ceramic was used to prepare automotive glass enamel. The results indicate that: (I) with the increase of Bi2O3/SiO2 ratio, the characteristic temperature of the base glass decreases, the coefficient of thermal expansion (CTE) and crystallization ability increases significantly, the crystallization temperature range becomes wider; (II) the crystallization activation energy of base glasses are in the range of 169~264 kJ/mol; (III) Bi2SiO5 and Bi2O2SiO3 metastable phases are mainly precipitated when the crystallization temperature is between 530 °C and 650 °C, while only Bi4Si3O12 phase is precipitated when the crystallization temperature is above 650 °C; (IV) crystallinity of base glass increases significantly with increasing heat treatment temperature, which is beneficial to improve the acid resistance of heat treated products; (V) automotive glass enamel was prepared by mixing 15R2O-25Bi2O3-10B2O3-50SiO2 glass-ceramic powder with copper-chrome black and varnish, and then printed on the automobile glass substrate. All the properties of the sintered enamel can meet the market requirements, and the acid resistance of our product is better than that of market products

Stress and strain analysis of Si-based III - V template fabricated by ion-slicing

Strain and stress were simulated using finite element method (FEM) for three III-V-on-Insulator (III-VOI) structures, i.e., InP/SiO2/Si, InP/Al2O3/SiO2/Si, and GaAs/Al2O3/SiO2/Si, fabricated by ion-slicing as the substrates for optoelectronic devices on Si. The thermal strain/stress imposes no risk for optoelectronic structures grown on InPOI at a normal growth temperature using molecular beam epitaxy. Structures grown on GaAsOI are more dangerous than those on InPOI due to a limited critical thickness. The intermedia Al2O3 layer was intended to increase the adherence while it brings in the largest risk. The simulated results reveal thermal stress on Al2O3 over 1 GPa, which is much higher than its critical stress for interfacial fracture. InPOI without an Al2O3 layer is more suitable as the substrate for optoelectronic integration on Si

CsPb(Br/I)3Perovskite Nanocrystals for Hybrid GaN-Based High-Bandwidth White Light-Emitting Diodes

The modulation bandwidth of white light emitting diodes (LEDs) is an important factor in visible light communication (VLC) system, which is mainly limited by the down-conversion materials. The broad spectrum and long lifetime of conventional light conversion materials represent an obstacle to future technological developments. Here, we show that inorganic semiconductor perovskite nanocrystals offer a promising alternative nanomaterial. Anion exchange between different perovskite nanocrystals by post-synthesis is a highly efficient protocol to tune the chemical composition and optoelectronic properties of lead halide perovskite nanocrystals. The fine-tuning of the nanocrystal fluorescence is achieved by 2 blending colloidal solutions of CsPb(Br/I)3 lead halide perovskites with different content of halide. The tunable optical emission and short fluorescence lifetime (< 5 ns) of the nanocrystals are exploited to realize white LEDs with a high modulation bandwidth (0.7 GHz), offering a potential route towards fast, energy efficient visible light communication