Wafer Scale Gallium Nitride Integrated Electrode Toward Robust High Temperature Energy Storage.

Gallium Nitride (GaN), as the representative of wide bandgap semiconductors, has great prospects in accomplishing rapid charge delivery under high-temperature environments thanks to excellent structural stability and electron mobility. However, there is still a gap in wafer-scale GaN single-crystal integrated electrodes applied in the energy storage field. Herein, Si-doped GaN nanochannel with gallium oxynitride (GaON) layer on a centimeter scale (denoted by GaN NC) is reported. The Si atoms modulate electronic redistribution to improve conductivity and drive nanochannel formation. Apart from that, the distinctive nanochannel configuration with a GaON layer provides adequate active sites and extraordinary structural stability. The GaN-based supercapacitors are assembled and deliver outstanding charge storage capabilities at 140 °C. Surprisingly, 90% retention is maintained after 50 000 cycles. This study opens the pathway toward wafer-scale GaN single-crystal integrated electrodes with self-powered characteristics that are compatible with various (opto)-electronic devices.

Silicon carbide single crystals for high-temperature supercapacitors.

Designing advanced electrode materials that can be reliably cycled at high temperatures and used for assembling advanced energy storage devices remain a major challenge. As a representative of novel wide bandgap semiconductors, silicon carbide (SiC) single crystals have broad prospects in high-temperature energy storage due to their excellent characteristics such as low thermal expansion coefficient, high temperature radiation resistance and stable chemical properties. In this work, an N-type SiC single-crystal material with a high-density porous structure was successfully designed and prepared by using an improved electrochemical anodic oxidation strategy. Besides, the N-type SiC single crystals were used in electrochemical energy storage as an integrated electrode material, exhibiting superior electrochemical performance. In addition, the high-temperature supercapacitor device assembled with ionic liquids has a wide operating temperature range and maintains a capacity of 88.24% after 5000 cycles at 150 °C. The reasons for its high energy storage performance are discussed through electrochemical tests and first-principles calculation methods. This study proves that the application of SiC single crystals in supercapacitor devices has great potential in the field of high-temperature energy storage, providing a reference for the further development of novel semiconductors in the field of energy storage and optoelectronic devices.

Experimental evaluation of the impact of ventilation on cooking-generated fine particulate matter in a Chinese apartment kitchen and adjacent room.

Cooking is one of the major contributors to indoor pollution. Fine particulate matter (PM2.5) produced during cooking commonly mix into adjacent rooms and elevates indoor PM2.5 concentrations. The risk of human exposure to cooking-generated PM2.5 is mainly related to the exposure duration and particulate matter (PM) concentration. The PM2.5 concentration is influenced by cooking methods and ventilation patterns. Range hoods and open windows are conventional strategies for lowering the concentration of cooking-generated particles. To decrease PM emissions, kitchen air supply systems have been proposed, providing alternative possibilities for kitchen ventilation patterns. The effects of cooking methods, air supply systems, range hoods, and windows on PM2.5 concentrations must be analyzed and compared. To understand and provide advice on reducing exposure to PM2.5 due to cooking activities, we measured the PM2.5 mass concentration in a kitchen and adjacent room during cooking. The identified factors, including cooking method, range hood use, window status, and air supply system, were varied based on orthogonal design. The delay time between the PM2.5 peak in the kitchen and that in the adjacent room was determined. The degree of exposure risk for cooking-generated PM2.5 was evaluated using the mean exposure dose. The results indicated that the mean PM2.5 mass concentration in the kitchen ranged from 22 to 2296 µg/m3. In descending order, the factors affecting the indoor PM2.5 concentration in the apartment studied were range hood use, cooking methods, window status, and air supply system. The PM2.5 peak in the adjacent room occurred 200-800 s later than that in the kitchen. Other conditions being constant in these experiments, the use of range hoods, air supply systems, and windows reduce exposure doses by 90%, 37%, and 51%, respectively. These research results provide insights for reducing human exposure to cooking-generated PM2.5.

Research Progress in Liquid Phase Growth of GaN Crystals.

As a wide band gap semiconductor, gallium nitride (GaN) has high breakdown voltage, excellent structural stability and mechanical properties, giving it unique advantages in applications such as high frequency, high power, and high temperature. As a result, it has broad application prospects in optoelectronics and microelectronics. However, the lack of high-quality, large-size GaN crystal substrates severely limit the improvement of electronic device performance. To solve this problem, liquid phase growth of GaN has attracted much attention because it can produce higher quality GaN crystals compared to traditional vapor phase growth methods. This review introduces two main methods of liquid phase growth of GaN: the flux method and ammonothermal method, as well as their advantages and challenges. It reviews the research history and recent advances of these two methods, including the effects of different solvents and mineralizers on the growth quality and performance of GaN crystals, as well as various technical improvements. This review aims to outline the principles, characteristics, and development trends of liquid phase growth of GaN, to provide more inspiration for future research on liquid phase growth, and to achieve further breakthroughs in its development and commercial application.

Measuring methane emissions during the installation of residential and commercial natural gas meters in China.

Methane is a potent greenhouse gas that accounts for one-quarter of the world's radiative forcing. Methane emissions from the natural gas sector are prevalent throughout the natural gas (NG) chain. Studies have shown that methane emissions from post-meter uses of natural gas are vastly understated. A surge in the number of natural gas users, for example, would amplify the climate impact of methane emissions during the installation of natural gas meters. Thus, quantifying methane emissions during the installation of natural gas meters is critical in light of severe global climate change and urgent reduction targets. In this study, we used a mass balance approach to calculate methane emissions during the separate installation of 1444 residential natural gas meters and 51 commercial natural gas meters. Our results revealed the methane emission had a fat tail distribution. Specifically, the estimated mean methane emissions for household users were 0.008 (0.001-0.022) kg per household and 0.192 (0.013-0.816) kg per commercial user. Extrapolating these statistics to the whole of China, total emissions from 2007 to 2021 were 3.80 million metric tons (MMt) CH4, with an annual average of 0.25 MMt. Notably, in terms of economic development and population size, the provinces with the highest methane emissions were concentrated in the southeast. Our findings close a gap in measuring CH4 emissions in China across the natural gas chain and provide data to support the reduction targets set and the development of reduction technologies.

Intrarenal small artery thrombosis in a transplant recipient patient infected with Covid-19 after kidney transplantation: A rare case report.

Currently, renal arteriovenous thrombosis induced by Covid-19 infection in patients after renal transplantation is very rare. We present a recent kidney transplant recipient who developed Covid-19 infection and later developed intrarenal small artery thrombosis. Finally, the patient's respiratory tract infection symptoms gradually disappeared after treatment. However, hemodialysis replacement therapy has to be continued due to the injury of the transplanted kidney function. In this case, we first reported that Covid-19 infection may induce intrarenal small artery thrombosis after kidney transplantation, which caused local ischemic necrosis of the transplanted kidney. We found that patients are at a high risk of Covid-19 infection at the early stage after kidney transplantation, and their clinical symptoms may be severe. In addition, even with anticoagulant therapy, Covid-19 infection may still increase the risk of thrombosis to some extent for patients who have undergone kidney transplantation, and we need to be alert to this rare complication in the future clinical work.

Gallium Nitride Based Electrode for High-Temperature Supercapacitors.

Gallium nitride (GaN) single crystal, as the representative of wide-band semiconductors, has great prospects for high-temperature energy storage, of its splendid power output, robust temperature stability, and superior carrier mobility. Nonetheless, it is an essential challenge for GaN-based devices to improve energy storage. Herein, an innovative strategy is proposed by constructing GaN/Nickel cobalt oxygen (NiCoO2  ï¼‰heterostructure for enhanced supercapacitors (SCs). Benefiting from the synergy effect between the porous GaN network as a highly conductive skeleton and the NiCoO2 with massive active sites. The GaN/NiCoO2 heterostructure-based SCs with ion liquids electrolyte are assembled and delivered an impressive energy density of 15.2 µWh cm-2 and power density, as well as superior service life at 130 °C. The theoretical calculation further explains that the reason for the energy storage enhancement of the GaN/NiCoO2 is due to the presence of the built-in electric fields. This work offers a novel perspective for meeting the practical application of GaN-based energy storage devices with exceptional performance capable of operation under high-temperature environments.

High-Performance Diamond Phototransistor with Gate Controllable Gain and Speed.

This paper presents a fabricated solar-blind phototransistor based on hydrogen-terminated diamond. The phototransistor shows a large photocurrent and enhancement of responsivity over conventional two-terminal diamond-based photodetector. These enhancement effects are owing to the internal gain of the phototransistor. The fabricated phototransistor exhibits a high photoresponsivity (R) of 2.16 × 104 A/W and a detectivity (D*) of 9.63 × 1011 jones, with gate voltage (VG) and drain voltage of approximately -1.5 V and -5 V, respectively, under 213 nm light illumination. Even at ultralow operating voltage of -0.01 V, the device records satisfactory performance with R and D* of 146.7 A/W and 6.19 × 1010 jones, respectively. By adjusting the VG, photocurrent generation in the device can be continuously tuned from the fast photoconductive effect to the optical gating effect with high optical gain. When VG increases from 1.4 to 2.4 V, the decay time decreases from 1512.0 to 25.5 ms. Therefore, responsivity, dark current, Iphoto/Idark, and decay time of the device can be well tuned by VG.

Research progress of large size SiC single crystal materials and devices.

SiC semiconductor is the focus of recent international research. It is also an important raw material for China to achieve carbon emission peak and carbon neutrality. After nearly 20 years of research and development, we focus on the three types SiC crystals, n-type, p-type and semi-insulating, indicating the development of Shandong University for crystal growth. And defects control, electrical property, atomic polishing, and corresponding device authentication all obtain great progress. Total dislocation density of 6-inch n-type substrates decreases to 2307 cm-2, where BPD (Basal Plane Dislocation) lowers to 333 cm-2 and TSD (Threading Screw Dislocation) 19 cm-2. The full width at half maximum (FWHM) (0004) rocking curves is only 14.4 arcsec. The resistivity reaches more than 1E + 12 Ω·cm for semi-insulating SiC and lower than 20 mΩ·cm for n-type SiC. The impurity concentrations in 6-inch high-purity semi-insulating (HPSI) SiC crystals reach extreme low levels. The devices made of various substrate materials have good performance.

Pinning and Anharmonic Phonon Effect of Quasi-Free-Standing Bilayer Epitaxial Graphene on SiC.

Epitaxial graphene on SiC without substrate interaction is viewed as one of the most promising two-dimensional (2D) materials in the microelectronics field. In this study, quasi-free-standing bilayer epitaxial graphene (QFSBEG) on SiC was fabricated by H2 intercalation under different time periods, and the temperature-dependent Raman spectra were recorded to evaluate the intrinsic structural difference generated by H2 time duration. The G peak thermal lineshift rates dω/dT showed that the H2 intercalation significantly weakened the pinning effect in epitaxial graphene. Furthermore, the G peak dω/dT value showed a perspicuous pinning effect disparity of QFSBEG samples. Additionally, the anharmonic phonon effect was investigated from the Raman lineshift of peaks. The physical mechanism responsible for dominating the G-mode temperature-dependent behavior among samples with different substrate coupling effects was elucidated. The phonon decay process of different samples was compared as the temperature increased. The evolution from in situ grown graphene to QFSBEG was determined. This study will expand the understanding of QFSBEG and pave a new way for its fabrication.

Influence of Different Heater Structures on the Temperature Field of AlN Crystal Growth by Resistance Heating.

Based on the actual hot zone structure of an AlN crystal growth resistance furnace, the global numerical simulation on the heat transfer process in the AlN crystal growth was performed. The influence of different heater structures on the growth of AlN crystals was investigated. It was found that the top heater can effectively reduce the axial temperature gradient, and the side heater 2 has a similar effect on the axial gradient, but the effect feedback is slightly weaker. The axial temperature gradient tends to increase when the bottom heater is added to the furnace, and the adjustable range of the axial temperature gradient of the side 1 heater + bottom heater mode is the largest. Our work will provide important reference values for AlN crystal growth by the resistance method.

Micropipes in SiC Single Crystal Observed by Molten KOH Etching.

Micropipe, a "killer" defect in SiC crystals, severely hampers the outstanding performance of SiC-based devices. In this paper, the etching behavior of micropipes in 4H-SiC and 6H-SiC wafers was studied using the molten KOH etching method. The spectra of 4H-SiC and 6H-SiC crystals containing micropipes were examined using Raman scattering. A new Raman peak accompanying micropipes located near -784 cm-1 was observed, which may have been induced by polymorphic transformation during the etching process in the area of micropipe etch pits. This feature may provide a new way to distinguish micropipes from other defects. In addition, the preferable etching conditions for distinguishing micropipes from threading screw dislocations (TSDs) was determined using laser confocal microscopy, scanning electron microscopy (SEM) and optical microscopy. Meanwhile, the micropipe etching pits were classified into two types based on their morphology and formation mechanism.

Dependence of conduction characteristics on compensation type and lattice structure of SiC photoconductive semiconductor switches.

Semi-insulating (SI) SiC photoconductive semiconductor switches were prepared using two compensation mechanisms: namely vanadium dopants compensation (4H- and 6H-SiC) and deep level defect compensation (4H-SiC). The bias voltage and current of the high-purity (HP) SI 4H-SiC photoconductive semiconductor switch (PCSS) with a channel length of 1 mm reached 24 kV and 364 A, respectively, and the minimum on-state resistance of approximately 1 Ω was triggered by laser illumination at a wavelength of 355 nm. The experimental results show that, in this case, the on-state characteristics of HP 4H-SiC PCSS are superior to those of the vanadium-doped(VD) 4H and 6H-SiC PCSS devices. HP 4H-SiC PCSS shows remarkable waveform consistency. Unlike for VD 4H and 6H-SiC PCSS, the current waveform of HP 4H-SiC PCSS exhibits a tailing phenomenon due to its longer carrier lifetime.

Retracted: Anticancer Action of Psilostachyin-A in 5-Fluorouracil-Resistant Human Liver Carcinoma are Mediated Through Autophagy Induction, G2/M Phase Cell Cycle Arrest and Inhibiting Extracellular-Signal-Regulated Kinase/Mitogen Activated Protein Kinase (ERK/MAPK) Signaling Pathway.

An editorial decision has been made to retract this manuscript due to breach of publishing guidelines, following the identification of non-original and manipulated figures. Reference: Jun Liu, Yan Liu, Yan Liu, Lei Huang, Guoliang Wang, Jun Wang, Xiangang Xu, Chengxian Shi, Jianzhao Huang: Anticancer Action of Psilostachyin-A in 5-Fluorouracil-Resistant Human Liver Carcinoma are Mediated Through Autophagy Induction, G2/M Phase Cell Cycle Arrest and Inhibiting Extracellular-Signal-Regulated Kinase/Mitogen Activated Protein Kinase (ERK/MAPK) Signaling Pathway. Med Sci Monit 2019; 25:6711-6718. 10.12659/MSM.916635.

The Influence of the Different Repair Methods on the Electrical Properties of the Normally off p-GaN HEMT.

The influence of the repair process on the electrical properties of the normally off p-GaN high-electron-mobility transistor (HEMT) is studied in detail in this paper. We find that the etching process will cause the two-dimensional electron gas (2DEG) and the mobility of the p-GaN HEMT to decrease. However, the repair process will gradually recover the electrical properties. We study different repair methods and different repair conditions, propose the best repair conditions, and further fabricate the p-GaN HEMTs devices. The threshold voltage of the fabricated device is 1.6 V, the maximum gate voltage is 7 V, and the on-resistance is 23 Ω·mm. The device has a good performance, which proves that the repair conditions can be successfully applied to the fabricate of the p-GaN HEMT devices.

Basal Plane Bending of Homoepitaxial MPCVD Single-Crystal Diamond.

We report herein high-resolution X-ray diffraction measurements of basal plane bending of homoepitaxial single-crystal diamond (SCD). We define SCD (100) as the base plane. The results revealed that growth parameters such as temperature, growth time, and basal plane bending of the substrate all affect the basal plane bending of SCD. First, the basal plane bending of SCD depends mainly on the substrate and becomes severe with increasing basal plane bending of the substrate. The SCD growth experiments show that the basal plane bending increases with elevated growth temperature and increased growth time. Finally, to understand the mechanism, we investigated the substrate-surface temperature distribution as a function of basal plane bending of SCD fabricated by chemical vapor deposition (CVD). This allowed us to propose a model and understand the origin of basal plane bending. The results indicate that an uneven temperature distribution on the substrate surface is the main cause of the base-plane bending of CVD diamond.

PM2.5 mass concentration variation in urban residential buildings during heating season in severe cold region of China: A case study in Harbin.

Recent years, people pay great attention to fine particle matter (PM2.5) in indoor environment due to its negative impacts on health. Household cooking and severe air pollutant aggravate indoor PM2.5 level, especially during heating season in severe cold region of China. To find the variation of actual household PM2.5 influenced by both cooking activities and penetration from outdoor environment, a field measurement of PM2.5 concentrations in living room of residential buildings was conducted in Harbin, China. Firstly, six households in urban residence were selected to monitor the indoor PM2.5 mass concentration sequentially. Simultaneously, outdoor PM2.5 concentrations, temperature and indoor occupants' behavior were collected. Secondly, indoor to outdoor (I/O) ratios of PM2.5 in each household during monitoring campaigns were calculated. Influence of cooking activities and outdoor penetration on indoor PM2.5 concentrations in living room were also analyzed. Thirdly, some discussions were done for explanation of variation of PM2.5 in urban residential buildings. Results showed that the average PM2.5 mass concentrations varied from 11.7 to 48.6 µg/m3 indoor, while average I/O ratio value ranged from 0.33 to 1.23. Cooking in kitchen had significant impact on PM2.5 mass concentrations in living room, especially when frying, which could lead to peak value of 456.8 µg/m3 within 10 min from background level. Penetration led to the indoor PM2.5 level approximately 2 h behind with outdoor PM2.5 concentrations in general residences.

Wave-shaped temperature dependence characteristics of the electroluminescence peak energy in a green InGaN-based LED grown on silicon substrate.

This study aimed to investigate temperature dependencies at different injection currents (ICs) of the electroluminescence (EL) spectra from a green InGaN/GaN light-emitting diode (LED) based on multiple quantum wells (MQWs) grown on a Si substrate in a wide range of ICs (0.001-350 mA) and temperatures (6-350 K). The results show that the temperature-changing characteristic of the EL peak energy gradually evolves from an approximately V-shaped temperature dependence into a wave-shaped (three-step blueshift) dependence with increasing IC. Finally, it emerges as an approximately inverted V-shaped temperature dependence. The behavior reflects the fact that the emission related to InGaN is significantly influenced by the changing recombination dynamics of carriers with rising temperature or IC. This is attributed to the presence in the MQW active region of a stronger carrier localization effect across three zones with different average In contents. Moreover, with the decline of the temperature at lower ICs, the temperature behavior of the external quantum efficiency (EQE) value is dominated by the deactivated non-radiative centers. This phenomenon occurs not only in the higher temperature range but also at lower temperatures due to more In-content-induced structural defects, which are confirmed by measurements of the integrated EL intensity as well as the EQE dependence on IC.

Finite element analysis of fiber-optic Fabry-Perot pressure sensors based on silicon diaphragms.

Fiber-optic Fabry-Perot pressure sensors based on silicon diaphragms of different thicknesses were fabricated using surface and bulk MEMS techniques in this study. The multi-beam interference resulting from multiple reflecting mirrors with the elastic deformation of the Fabry-Perot sensor was simulated by finite element analysis. The pressure sensitivities of the sensors with different diaphragm thicknesses and the relationship between the pressure and the wavelength shift were simulated. The simulation results were in good agreement with the test results. This study provides guidance for future sensor models and parameter design.