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The electrothermal coupling effect on transistors is an intractableness of power circuits optimization, particularly for recent novel materials with high performance but low thermal conductivity, like beta-gallium oxide ( $\beta $ -Ga2O3). Self-consistent calculations of electrothermal coupling effect in $\beta $ -Ga2O3 metal-oxide–semiconductor field-effect transistors (MOSFETs) are essential to assess the thermal behavior from device to circuit level. In this article, we proposed a physics-based compact electrothermal model of $\beta $ -Ga2O3 MOSFETs. Analytical solutions of current, terminal charge, and channel temperature are obtained based on surface potential, Ward-Dutton’s charge-partitioning scheme, and Fourier’s heat conduction law, respectively. Moreover, temperature-dependence mobility and device power dissipation are employed to couple electrical and thermal properties by embedding a two-order RC thermal subcircuit. The model is rigidly verified by comparing against experimental data and 3-D-FEM simulations under different process conditions. Especially, the calibrated model is used to evaluate the effect of technology parameters such as substrate material and thickness on boost converter performance, providing design space in design-technology co-optimization (DTCO) flow.

This manuscript aims to enhance the production efficiency while maintaining the electric properties of the dynamic random-access memory capacitor dielectric ZrO2 by optimizing its growth processes. This is achieved through oxidizer engineering by increasing the O3 flux (1k sccm to 10k sccm) and using an extremely fast pulse time (1.5 s) during the atomic layer deposition of ZrO2. This “short pulse - high oxidizer flux” method elevates the k value, effectively reduces leakage, and cuts off the growth time. The application of this method yields ZrO2-based capacitors of low leakage current densities ( ${2}\times {10}^{-{8}}$ A/cm2) and low equivalent oxide thicknesses of 0.55 nm (at 0.5 V, 10k sccm O3 flux), holding significant potential as a key facilitator for future ultra-high-density DRAM systems.

Antiferromagnets (AFMs) are ideal materials to boost neuromorphic computing toward the ultrahigh speed and ultracompact integration regime. However, developing a suitable AFM neuromorphic memory remains an aspirational but challenging goal. In this work, we construct such a memory based on the CoO/Pt heterostructure, in which the collinear insulating AFM CoO shows a strong perpendicular anisotropy facilitating its electrical readout and writing. Utilizing the unique nonlinear response and bipolar fading memory properties of the device, we demonstrate a multidimensional reservoir computing beyond the traditional binary paradigm. These results are expected to pave the way toward next-generation fast and massive neuromorphic computing.

As the feature size of dynamic random access memories (DRAM) continues to scale down, the shrunk storage capacitors have met essential challenges, namely, the insufficient capacitances and the excessive leakage currents. In this article, the electrical properties of silicon-doped zirconia (ZrO2) films, with the goal of improving their properties for use as capacitor dielectric for DRAM, were investigated. The results indicated that the introduction of an appropriate amount of Si can increase the portion of the tetragonal crystal phase in ZrO2 dielectric, thereby leading to an increase in the dielectric constant by 26.8%. Even higher Si content leads to the degradation of the crystal structure. Additionally, Si doping likely deepens the depth of defect energy levels in the dielectric, which may suppress the leakage current of the metal–insulator–metal (MIM) capacitors. Compared with the un-doped samples, the leakage current was reduced by 60.2% at the operating voltage of 0.8 V. The equivalent oxide thickness (EOT) was reduced by 17.5% at the standard leakage current density ( $\lt 1 \times 10^{-{7}}$ A/cm2 at 0.8 V). It demonstrated that the Si doping strategy can effectively enhance the capacitance of capacitors and suppress leakage current, thereby addressing the critical issues associated with ZrO2-based MIM capacitors.

Recognition and judgment of X-ray computed tomography (CT) images play a crucial role in medical diagnosis and disease prevention. However, the storage and calculation of the X-ray imaging system applied in the traditional CT diagnosis is separate, and the pathological judgment is based on doctors’ experience, which will affect the timeliness and accuracy of decision-making. In this paper, a simple-structured reservoir computing network (RC) is proposed based on Ga2O3X-ray optical synaptic devices to recognize medical skeletal CT images with high accuracy. Through oxygen vacancy engineering, Ga2O3X-ray optical synaptic devices with adjustable photocurrent gain and a persistent photoconductivity effect were obtained. By using the Ga2O3X-ray optical synaptic device as a reservoir, we constructed an RC network for medical skeletal CT diagnosis and verified its image recognition capability using the MNIST data set with an accuracy of 78.08%. In the elbow skeletal CT image recognition task, the recognition rate is as high as 100%. This work constructs a simple-structured RC network for X-ray image recognition, which is of great significance in applications in medical fields.

This article reports the time-dependent dielectric breakdown (TDDB) reliability of zirconia (ZrO2)-based MIM capacitors with sub-0.7-nm equivalent oxide thicknesses (EOT). Results indicate that substituting the top part of the ZrO2 with an Al2O3/ZrO2/Al2O3 (AZA) stack dramatically improves the reliability of the ultra-thin capacitors. The origin is attributed to Al-doping forming an amorphous crystalline phase; such phase lowers the average defect generation rate in the dielectric, which is crucial for slowing the formation of breakdown paths. As a result, the highest ${E} _{\mathbf {\textit {TDDB}}}$ of 4.18 MV/cm (0.01% failure rate @ 10 years) has been achieved in 5.0 nm ZrO2-AZA (ZAZA) devices (EOT = 0.63 nm). This work provides an effective approach to mitigate the reliability issues in ultra-thin dielectrics using fabrication technologies compatible with industrial applications.

We experimentally studied the influence of current sharing among filaments on the initiation of thermal runaway and protection against it in a multifilament coated conductor wound spirally on a round core. We artificially introduced a local defect near one edge of a 4-mm-wide multifilament coated conductor as well as a monofilament coated conductor by using a fine drill bit. We wound each coated conductor on a glass fiber-reinforced plastic (GFRP) core and set several voltage taps on their both edges to measure the voltages in longitudinal (both edges) and transverse directions. We compared thermal runaway current, above which thermal runaway initiates, of multifilament coated conductor with that of monofilament coated conductor. We also compared their time constants of current ramping down, below which the coated conductors are protected against degradation after thermal runaway.

Beta-gallium oxide ( $\beta $ -Ga2O3) has emerged as a promising semiconductor material for high-voltage, high-temperature, and radiation-resistant electronics, offering performance advantages that surpass those of silicon and other wide bandgap semiconductors. Breakthroughs in the fabrication process and structure designing have led to the rapid development of vertical $\beta $ -Ga2O3 power transistors and shown their potential superiority for next-generation power devices. In this article, we present a review of major types of vertical $\beta $ -Ga2O3 transistors including current aperture vertical electron transistors (CAVETs), vertical fin-channel field-effect transistors (FinFETs), vertical diffused barrier field-effect transistors (VDBFETs), and U-shaped trench-gate metal-oxide-semiconductor field-effect transistors (UMOSFETs). We present their operation principles, performance achievements, design evolutions, and detailed optimizations with mechanism research. Comparisons are highlighted to analyze the advantages and inadequacies caused by their unique process approaches and enhancement-mode realizations. In the end, we address challenges and outlooks for the future development of vertical $\beta $ -Ga2O3 transistors.

We proposed an electrothermal aging (ETA) technology to improve stability of threshold voltage ( ${V} _{\text {TH}}$ ) in fabricated NiO/ $\beta $ -Ga2O3 heterojunction-gate FET (HJ-FET). Firstly, the HJ-FET is treated by ETA with a gate stress ( ${V} _{\text {G},\text {Str}}$ ) of −8 V and a thermal stress rising to 60 °C. An interface dipole ionization model is proposed to explain the ETA mechanism. The two kinds of interface dipoles are permanently ionized under electrothermal stress, leading to a thinned space charge region (SCR) as well as the reduced recombination centers concentrations at heterojunction (HJ) interface, which is responsible for the negative and positive shift of the ${I}$ – ${V}$ curves for the HJ-FET and HJ-diode under gate negatively biased, respectively. Secondly, the device treated by ETA is placed for 100 days without stresses at room temperature (ETA + 100D), the forward electrical properties of the devices remain almost unchanged with the gate stress time, and fully consistent with the performance of the device with just completed ETA treatment, proving the credibility of the ETA method to improve stability. Thirdly, the reliability of the device was assessed by negative bias temperature instability (NBTI) and was found to be greatly enhanced. Significantly, at 40 °C, the shift ratio of ${V} _{\text {TH}}$ decreases greatly to 0.4% after ETA + 100D from 31% before ETA. Furthermore, the device exhibits high stability with an extremely low ${V} _{\text {TH}}$ shift ratio of 2.4% even up to 200 °C. Our work demonstrates the great potential of $\beta $ -Ga2O3 HJ devices after ETA for a stable operation in extreme environments.

Ultra wide bandgap semiconductor beta-gallium oxide ( $\beta $ -Ga2O3) has the potential in fabricating the next generation of power devices applied at high temperature and high voltage due to its superior material properties and cost competitiveness. However, the performance of the existing $\beta $ -Ga2O3 power diodes is far from the theoretical value because of the restriction of interface quality and edge electric field crowding effect. In this review, we introduce several effective interface engineering and edge termination techniques commonly used in vertical $\beta $ -Ga2O3 diodes, highlighting their design principles, key fabrication processes, physical mechanism, and merit/demerit. To realize the actual applications, the representative large-size $\beta $ -Ga2O3 diodes that can allow large level current to flow are also discussed. In addition, possible optimization strategies for these techniques are proposed for researchers’ reference. This article will help researchers understand the current study status of vertical $\beta $ -Ga2O3 diodes and inspire researchers for future innovation in this emerging and exciting field. Moreover, the techniques and optimization strategies mentioned can also be applied to other semiconductors.

The 2T0C memory array based on InGaZnO4 thin-film transistors (IGZO-TFTs) was proposed as a new architecture of dynamic random access memory (DRAM) due to its extremely low off-current and potential for monolithic 3-D stack. However, the multilayer stacked 2T0C memory array probably brings severe self-heating issue from the thermal crosstalk among layers. In this article, the 2T0C memory array model was built based on the material properties, electron transport characteristics of IGZO, and basic Fourier heat flow equation. According to the proposed electrothermal model, we found that the electron Joule heat in read operation accounts for the main part of heat generation in the whole operation cycle. The thermal characteristics of different stacked 2T0C cell structures will give advanced guidance for the thermal management scheme of 2T0C DRAM configuration. In addition, the temperature rising of 2T0C cell increases the off-state leakage, resulting in severe degradation of the retention time. It partly attributes to that the oxygen vacancies (VO) generate more electrons at elevated temperatures. Moreover, the significance of low density of VO state is emphasized for the temperature stability of 2T0C cell.

In this letter, the self-powered solar-blind photodetector based on amorphous (a-) SnOx/crystalline (c-) Ga2O3 pn heterojunction with swift response speed has been successfully demonstrated. Increased hole concentration in a-SnOx by enhanced Sn2+ component under annealing improves the self-powered photoresponse performance. A highly precise test scheme without external supply captures the intrinsically swift response speed. The photodetector exhibits an impressive rise/decay time of 0.18/1.04 ms and responsivity of 7.08 A/W at 0 V bias, ranking into the top tier in all self-powered Ga2O3 photodetectors. This study provides a referenceable self-powered detector structure with amorphous/crystalline pn heterojunction.

Despite yet achieved ultrahigh responsivity, slow response speed remains the main short slab of Ga2O3 solar-blind photodetector (SBPD). Here, we reported a fast speed SBPD with sub-10 ms response speed by radio frequency sputter at room temperature at an optimized growth power, which even surpasses most counterparts with high temperature process. The enhanced response speed is contributed to higher binding energy and less trap states. Moreover, the device shows excellent photoresponse characteristics, including low dark current of 1.57 pA, decent responsivity of 0.81 A/W, and high photo to dark current ratio of ${6}.{6}\times {10} ^{{6}}$ . This study affords a possibility of swift Ga2O3 SBPD via a facile way without high temperature process engineering.

In this study, we fabricated superb $\beta $ -Ga2O3 Schottky barrier diodes (SBDs) with high breakdown voltage ( ${V}_{\text {br}}{)}$ and low leakage through combining platinum oxide (PtO $_{\text {x}}{)}$ and anodic self-aligned mesa termination (SAMT). The PtOx that forms a high barrier with $\beta $ -Ga2O3 enables the SAMT to function sufficiently. The in-situ annealing dry etch process repair the mesa sidewall and improve the Schottky contact well. SBDs with different mesa-etched depths ( ${D}_{\text {ee}}{)}$ were systematically studied, including 0, 0.3, 0.6, 0.9, and $1.2~\mu \text{m}$ . The results showed that the ${V}_{\text {br}}$ of the PtOx/ $\beta $ -Ga2O3 SBD increased from 1120 V to 2738 V, yielding a high power figure of merit (PFOM) of 1.02 GW/cm2. Meanwhile, the device maintained a less than $10~\mu \text{A}$ /cm2 leakage current density until -2000 V. Devices with radii of 200, 100, and $50~\mu \text{m}$ obtained highest ${V}_{\text {br}}$ of 2508, 2772, and 2738 V at a ${D}_{\text {ee}}$ of $1.2~\mu \text{m}$ , respectively. The devices can be passivated by SU-8 without ${V}_{\text {br}}$ degradation. This work provides an effective method for further improving the performance of $\beta $ -Ga2O3 SBDs and promotes the application of $\beta $ -Ga2O3 power diodes.

We experimentally studied the quench characteristics of a coated conductor wound spirally on a round metal core, which is similar to CORC cables. We used the simplest sample configuration, in which one coated conductor was wound sparsely in one layer and which enabled us to attach the voltage taps to the core as well as the coated conductor. We measured the voltages along the coated conductor, those along the core, and those between the coated conductor and the core. The hot-spot temperature and the current shared by the core were calculated by using the measured voltages. The impact of the current sharing on the reduction of hot-spot temperature is discussed.

Ultrasonic propagation in coal seams is accompanied by heat transfer, which has the potential to increase coal seam permeability, enhance coalbed methane (CBM) recovery, and prevent coal and gas outbursts. Therefore, it is important to analyze the effects of heat transfer by ultrasonic vibration on CBM recovery and evaluate the prospects of engineering applications of ultrasonic heating technology. In this study, the factors affecting heat transfer by ultrasonic vibration were analyzed theoretically; then, CBM recovery under the condition of ultrasonic heating was simulated by establishing a coupled acoustic–thermal–mechanical–hydrological model. The correctness of acoustic–thermal model was validated by matching simulated data with experimental data. And the accuracy of the gas flow model was verified by comparing the production data from CBM extraction boreholes with the simulated data. The research results were as follows: heat transfer by ultrasonic vibration was affected by frequency and sound pressure. When the ultrasonic frequency varied from 30 to 40 kHz and the sound pressure varied from 0.1 to 0.12 MPa, the lower the frequency, the higher the sound pressure, and the better the ultrasonic vibration heat transfer effect. In addition, the thermal expansion volumetric strain of the coal matrix caused by the ultrasonic heating of coal seams was weaker than the shrinkage volumetric strain of the coal matrix caused by gas desorption, improving the porosity and permeability of the coal seams. Furthermore, the gas drainage standard area increased by 20.8 m2after 720 days of CBM recovery when replacing conventional CBM recovery with ultrasonic-assisted CBM recovery. With a production time of 720 days, the maximum production of CBM after ultrasonic excitation at a frequency of 40 kHz and a sound pressure of 0.10 MPa increases from 3744 to 9740 m3/day compared to conventional excitation. Our fully coupled acoustic–thermal–mechanical–hydrological model can improve current understandings of heat and mass transfer in thermal simulation of ultrasonic-enhanced CBM recovery.

High-quality β-Ga2O3films were epitaxially grown by using metalorganic chemical vapor deposition (MOCVD) with different donor concentrations, and their shallow donor states were investigated by the temperature-dependent Hall measurement and secondary ion mass spectroscopy (SIMS) analysis. Two donor levels with ionization energies of ∼36 and ∼140 meV were extracted. It is found that the unintentional doping (UID) effects in MOCVD contribute substantially to both these two levels: the first donor level may come not only from silicon doping but also from unintentional substitution of carbon for Ga sites, and the second donor level probably comes from doubly charged defects related to unintentional H doping. By analyzing the relationship between the growth conditions and donor states, combined with density functional theory calculations, it is found that reducing the oxygen partial pressure during the growth might be a feasible way to reduce the UID effect. This work paves the way to the precise control of carrier density in Si-doped MOCVD β-Ga2O3films.

Self-powered solar-blind photodetector (SBPD) promises potential applications that urgently need portability and low-power consumption. Herein, an ultrasensitive self-powered p-n heterojunction SBPD based on amorphous NiO and single crystal Ga2O3 has been reliably achieved. The device exhibits a high photo-to-dark-current ratio of ${3}\times {10}^{{6}}$ , ultrahigh responsivity ( ${R}$ ) of 5 A/W, and specific detectivity of ${1.6}\times {10}^{{14}}$ Jones under 254 nm illumination at 0 V, with a solar-blind/visible rejection ratio ( ${R}_{\text {254 nm}}/{R}_{\text {460 nm}}$ ) of ${2}\times {10}^{{4}}$ . Notably, the open circuit voltage can reach 1.3 V and the response speed is significantly less than 1 ms. The comprehensive performance of the device exceeds most reported state-of-the-art Ga2O3 self-powered SBPDs, which is mainly attributed to amorphous NiO/crystalline Ga2O3 vertical junction structure with low-defect interface and strong built-in electric field. This work provides novel design strategies for the future development of high-performance self-powered photodetector.

In this work, a $\beta $ -Ga2O3 field-effect rectifier (FER) with a p-NiOx gate aimed at low conduction loss, low leakage current, and capability of on-chip integration has been demonstrated. The proposed FER exhibits a low turn-on voltage ( ${V}_{\text {on}}{)}$ of 0.85 V comparable to Schottky barrier diodes (SBDs). The p-NiOx in FER offers an additional conduction path at high forward bias, which enhances the forward current. Compared with the lateral heterojunction diode (HJD) and SBD on the same substrate, the FER shows the best tradeoff between ON-state and OFF-state power dissipation, including lower ${V}_{\text {on}}$ than HJD (~41% of HJD) and lower leakage current than SBD (four orders of magnitude lower). The merits of this structure also extend to the high-temperature operation regime of the device. Good rectification characteristics of FER are observed at elevated temperatures. The proposed FER with low ${V}_{\text {on}}$ , high-voltage blocking capability and process compatibility with field-effect transistors (FETs) has the potential of being used as a low-power loss rectifier in future $\beta $ -Ga2O3 power integrated circuits (ICs).

In this work, we demonstrate a novel conductivity-controlled junction termination extension (JTE) technique using p-type NiO—a key element for the potential commercialization of Ga2O3 power devices. The surface electric field at the Schottky edge is effectively suppressed by the p-type NiO JTE. Simultaneously, it can control the concentration of p-type NiO to maximize the breakdown voltage ( ${V}_{\text {br}}$ ) by changing the gas atmosphere during magnetron sputtering growth. The electrical characteristics of the $\beta $ -Ga2O3 Schottky barrier diodes (SBDs) with p-type NiO JTE are studied systematically. All $\beta $ -Ga2O3 SBDs with JTE show great advantages in terms of device performance parameters whether at room temperature or high temperature, which indicates the effectiveness of p-NiO JTE in reducing the fringe electric field. In particular, the $\beta $ -Ga2O3 SBDs with an optimized hole concentration of approximately $10^{{17}}$ cm $^{-{3}}$ for NiO in the JTE region exhibit a low specific ON-resistance of 2.9 $\text{m}\Omega $ cm2 and a high ${V}_{\text {br}}$ of 2.11 kV, yielding a high power figure-of-merit (PFOM) of 1.54 GW/cm2. Our results demonstrate the great potential of p-NiO as a controllable and reliable technique for junction engineering in $\beta $ -Ga2O3 power devices.

Superior performance $\beta $ -gallium oxide ( $\beta $ -Ga2O3) junction barrier Schottky (JBS) diode with a forward conduction current of 5.1 A (@2 V) and reverse breakdown voltage of 1060 V with an area of ${3} \times {3}$ mm2 is presented. Meanwhile, the high power figure of merit (PFOM) of 0.72 GW/cm2 is attributed to the implementation of the pn heterojunction and beveled field plate for a ${0}.{1} \times {0}.{1}$ mm2 diode. The switching characteristics of large-size $\beta $ -Ga2O3 JBS after encapsulation reveal a short reverse recovery time of 26.8 ns under switching conditions of di / dt up to 400 A/ $\mu \text{s}$ . In addition, a hybrid half-wave (HW) Cockcroft–Walton (CW) voltage multiplier is built first together with commercial SiC SBD, and the results show the competitive characteristics of $\beta $ -Ga2O3 JBS for SiC SBD, such as the almost same multiplication factor up to 3.81 in four-stage hybrid voltage multipliers compared with an all-SiC SBD-based circuit. The circuit efficiency is approximately 86.07% for $\beta $ -Ga2O3 diode-based hybrid voltage multipliers. These results demonstrate the enormous application potential of $\beta $ -Ga2O3 JBS significantly.

Metal–insulator–metal (MIM) capacitors based on zirconia (ZrO2) are widely used in dynamic random access memories (DRAMs). As the smaller and smaller feature size in DRAM chips requires higher and higher capacitance density, it is necessary to minimize the equivalent oxide thickness (EOT) of ZrO2, or maximize its dielectric constant ( ${k}$ ) while maintaining low leakage currents. Annealing is an effective method to achieve high ${k}$ -values. In this article, we report the impact of two mainstream annealing methods on the electrical properties of ZrO2-based MIM capacitors. The results showed that the dielectric constant of ZrO2 reached 41.5 after postdeposition anneal (PDA) at 350 °C, while grazing incidence X-ray diffraction (GIXRD) measurements indicated the formation of high- ${k}$ tetragonal phase. In contrast, similar dielectric constant enhancement requires much higher temperature (450 °C) for postmetallization anneal (PMA). When similar high- ${k}$ value was reached, the leakage current density of PDA samples was three orders of magnitude lower than that of PMA ones at 0.8 V. Additionally, lower annealing temperature also decreases the parasitic EOT at the interface, which was formed by the interaction of ZrO2 and TiN electrodes. Overall, we found PDA is more beneficial for achieving a higher dielectric constant (>40), lower leakage currents, and lower EOT at lower temperatures compared with PMA, and potentially more suitable for industrial DRAM fabrication process.

High-performance $\beta $ -Ga2O3 U-shaped trench-gate metal-oxide-semiconductor field-effect transistor (UMOSFET) has been demonstrated. Nitrogen ions implantation was employed to form current blocking layer. Electrons in the blocking layer can accumulate in the area near the U-shaped groove and form a conductive channel to promote current generation at a positive gate bias. The UMOSFET with an applicable threshold voltage of 4.2 V was achieved by modulating the concentration of implanted nitrogen ions. A high current density of 702.3 A/cm2, a low on-resistance of 10.4 $\text{m}\Omega \cdot $ cm2, and a decent breakdown voltage of 455 V (at ${V}_{\text {G}}=0$ V) were obtained for UMOSFET with N ions concentration of ${5}\times {10} ^{{18}}$ cm $^{-{3}}$ . The UMOSFET in this work offers exceptional advantages in fabrication of high-performance E-mode vertical $\beta $ -Ga2O3 MOSFETs, facilitating the development of $\beta $ -Ga2O3 power electronics devices.

In this article, we experimentally study the instability of the key electrical characteristic for the fabricated ${\beta }$ -Ga2O3 MOSFET under positive bias stress (PBS) and negative bias stress (NBS), such as threshold voltage ( ${V}_{{\mathrm {TH}}}$ ), ON-resistance ( ${R}_{{\mathrm {on}}}$ ), subthreshold slope (SS), and hysteresis. An ionized traps model is proposed to explain the instability, which depicts the traps and interfaces states capturing/releasing electrons from the channel. We find nonuniform instability mechanisms. Under the PBS of ${V}_{GS} = 4$ V for 1000 s, the ${V}_{{\mathrm {TH}}}$ and ${R}_{{\mathrm {on}}}$ are increased by 0.8 V and 19%, respectively. The constant interface state density indicates that this instability is caused by border traps in the gate oxide capturing electrons from channel. For the NBS of ${V}_{GS} = -4$ V for 1000 s, the variation in the ${V}_{{\mathrm {TH}}}$ and ${R}_{{\mathrm {on}}}$ is −0.54 V and −8.8%, respectively. The instability is attributed to both the border traps and interface states, and the net increase in activated interface states is $2.25\times10$ 11 cm−2 extracted from hysteresis. Unlike the PBS, the interface states release electrons to bulk traps, and thus the activated interface state density changes. A good agreement with experimental results shows that the proposed model could accurately describe the instability mechanism under both PBS and NBS. These results provide guidance for identifying defects, optimizing device structure, and fabrication process to improve the reliability of $\boldsymbol {\beta } $ -Ga2O3 MOSFET.

Resistive switching random access memory (RRAM) is one of the most promising candidates with high-density three-dimensional integration characteristics for next-generation nonvolatile memory technology. However, the poor uniformity issue caused by the stochastic property of the conductive filament (CF) impedes the large-scale manufacture of RRAM chips. Subulate array has been introduced into the RRAM to minimize the CF randomness, but the methods are cumbersome, expensive, or resolution-limited for large-scale preparation. In this work, Si subulate array (SSA) substrates with different curvature radii prepared by a wafer-scale and nanoscale-controllable method are introduced for RRAM fabrication. The SSA structure, which induces a quasi-single CF or a few CFs formed in the tip region (TR) of the device as evidenced by the high-resolution transmission electron microscopy and energy dispersive spectroscopy characterization, dramatically improves the cycle-to-cycle and device-to-device uniformity. Decreasing the curvature radius of the TR significantly improves the device performance, including switching voltages, high/low resistance states, and retention characteristics. The improved uniformity can be attributed to the enhanced local electric field in the TR. The proposed SSA provides a low-cost, uniform, CMOS-compatible, and nanoscale-controllable optimization strategy for the large-scale integration of highly uniform RRAM devices.

β-Ga2O3power diodes were expected to possess low turn-on voltage (Von), low reverse leakage (JR), and high blocking capability for low power losses. In this work, a low Von(0.48 V) β-Ga2O3heterojunction barrier Schottky diode (HJBS) with tungsten Schottky contact was achieved. Benefitting from the lateral depletion of p+-NiO to suppress JRoriginating from the low Schottky barrier, the blocking capability of β-Ga2O3HJBS was enhanced. The spacing width of p+-NiO was systematically studied to reveal its modulation effect on forward and reverse characteristics. This work provides a promising strategy for improving rectifier efficiency of β-Ga2O3diodes.

β-Ga2O3Schottky barrier diodes (SBDs) with low-defect epitaxial surface and effective termination are essential for realizing excellent blocking characteristics. This work systematically studied oxygen annealing at various temperatures, optimizing the epitaxial surface by reducing the surface roughness and dislocation density. Combined with mesa termination, the results showed that the breakdown voltage (Vbr) significantly increased from 845 V to 1532 V. The device with a 3 × 3 mm2anode size was fabricated simultaneously, and the high forward currents of 8.7 A@2 V and Vbr> 700 V were achieved. This work shows a possible solution for the commercialization of β-Ga2O3SBDs.

Drawing inspiration from biology, neuromorphic systems are of great interest in direct interaction and efficient processing of analogue signals in the real world and could be promising for the development of smart sensors. Here, we demonstrate an artificial sensory neuron consisting of an InGaZnO4(IGZO4)-based optical sensor and NbOx-based oscillation neuron in series, which can simultaneously sense the optical information even beyond the visible light region and encode them into electrical impulses. Such artificial vision sensory neurons can convey visual information in a parallel manner analogous to biological vision systems, and the output spikes can be effectively processed by a pulse coupled neural network, demonstrating the capability of image segmentation out of a complex background. This study could facilitate the construction of artificial visual systems and pave the way for the development of light-driven neurorobotics, bioinspired optoelectronics, and neuromorphic computing.

Infrastructure-as-a-service clouds are becoming ubiquitous for provisioning virtual machines on demand. Cloud service providers expect to use the least resources to deliver the best services. As users frequently request virtual machines to build virtual clusters and run MapReduce-like jobs for big data processing, cloud service providers intend to optimise the virtual cluster to minimise network latency and subsequently reduce data movement cost. In this paper, we focus on the virtual machine placement issue for provisioning virtual clusters with minimum network latency in clouds. We define the distance as the latency between virtual machines and use it to measure the affinity of a virtual cluster. Such metric of distance indicates the considerations of virtual machine placement and the topology of physical nodes in clouds. Then, we formulate our problem as the classical shortest distance problem and solve it by building an integer programming model. A greedy virtual machine placement algorithm is designed to get a compact virtual cluster. Furthermore, an improved heuristic algorithm is also presented for achieving a global resource optimisation. The simulation results verify our algorithms and the experiment results validate the improvement achieved by our approaches.

String similarity join is an essential operation of data quality management and a key step to find the value of data. An incremental processing framework for string similarity join is proposed in this paper. Compared with the batching processing model, it can avoid the heavy time cost and the space cost brought by the duplicate similarity computation among historical strings and is suitable for processing data streams. We implement two algorithms: Inc-Join and Inp-Join. Inc-Join runs on a stand-alone machine while Inp-Join runs on a cluster with Spark environment. The experimental results show that this incremental processing framework can reduce the amount of string matching without affecting the join accuracy. When the data quantity becomes large, Inp-Join can make full use of the advantage of parallel processing and obtain a better performance than Inc-Join.

The diet composition and contribution ratios for juvenile Chinese mitten crab Eriocheir sinensiscan vary with different feeding modes during pond culturing. To investigate this, the stomach contents of juvenile crabs and the contributions of different food sources to their growth were compared across three feeding modes: alligator weed Alternanthera philoxeroidesalone (Diet 1), formulated diet feed alone (Diet 2), and a 1:1 mixture of A. philoxeroidesand the formulated diet (Diet 3). The analysis utilized 18 S rDNA high-throughput sequencing and carbon and nitrogen stable isotopes. There were five replicates for each treatment group, and the experimental period was 120 d. The results showed that the diversity of the food composition in the stomach contents of the juvenile crabs was significantly lower (P < 0.05) with Diet 2 than with Diets 1 and 3.The seven phyla with the highest relative abundances in the stomach contents in descending order were Chloroplastida; Stramenopiles, Alveolata, and Rhizaria (SAR); Arthropoda; Cryptomycota; Phragmoplastophyta; Rotifera; and Eukaryota. The highest abundance of Phragmoplastophyta was 12.96 % with Diet 1, 53.66 % with Diet 2 %, and 8.23 % with Diet 3. The stable isotopes analysis showed that Diet 1 resulted in the lowest δ13C‰ values, whereas the δ15N‰ values were not significantly different among the three groups, indicating that there were differences in the food compositions of the juvenile crabs with the different feeding modes. The main food source for juvenile crabs fed Diet 1 was A. philoxeroides, with an average contribution of 28.91 % whereas that for juvenile crabs fed Diets 2 and 3 was the formulated feed, with average contributions of 33.35 % and 33.15 %, respectively. Particulate organic matter was the secondary food for all three diets. Therefore, in the juvenile crab pond culture feeding mode, the addition of a formulated feed when A. philoxeroideshas a contribution ratio of 10.39 % can improve feed utilization. This study can provide a scientific reference and theoretical basis for the promotion of the formulated feed feeding mode and the development of A. philoxeroidesas a vegetal feed added to the formuated feed of juvenile Chinese mitten crabs.

Micro-structures of the pore-fracture size distribution of target sandstone samples are studied through high-pressure mercury intrusion (HPMI) experiments, and the compressibility coefficient is quantitatively described by using overlying pressure porosity–permeability tests. Then, four single and multifractal models were used to quantitatively describe the fractal characteristics of mercury intrusion curves, and the relationship between different fractal models and pore structure parameters is analyzed. Furthermore, the applicability of fractal models in characterizing pore-fracture structures was explored. The results are as follows: (1) fractal model results show that fractal dimensions of type A by using Sierpinski (DS) and thermodynamics models (DM) are larger than those of type B, and fractal dimensions of type A by using Menger (DM) and multifractal models (D–10–D10) are smaller than those of type B. (2) The Menger model is used to describe heterogeneity of smaller pore size distribution, which is proportional to volume percentage of pores with the diameter smaller than 100 nm; the thermodynamic model is used to describe heterogeneity of medium pore size distribution, which is proportional to the volume percentage of pores with a diameter of 100∼1000 nm; The Sierpinski model is used to describe heterogeneity of larger pore size distribution, which is proportional to volume percentage of pores with the diameter larger than 1000 nm; (3) permeability decreases in the form of power function with the increase of confining pressure, and the compressibility coefficient and permeability variation coefficient decrease with the increase of the compressibility coefficient. There is no significant correlation between the compressibility coefficient, permeability variation coefficient, and pore structure parameters.

Remote data storage is a promising service and deployed in large-scale. The verification of data integrity is an important measure to protect the data from data corruption or loss in remote data storage environments. Current verification algorithms are mainly oriented to the service providers who may provide the false verification metadata or force the user to take fewer verification requests owing to the verification expense. To solve these issues, we propose a probabilistic verification algorithm to execute the routine verification and apply the homomorphism-based method to perform the challenge verification. The algorithm improves the metadata generation and innovates the metadata replacement to decrease the cost of verification and avoid the limitation of the traditional hash-based verification only executing for finite rounds. Theoretic analysis and simulation results demonstrate that our algorithm resists the spoofing attack as well as the excessive computation overhead at the expense of less cost in terms of verification data storage, transmission, and computation.

AbstractMap Reduce is emerging as an important programming model for data-intensive applications. It is widely used in a variety of different environments to deal with the services of big data processing. In order to adapt to these platforms, the original implementation of Map Reduce framework has been extended and enhanced. This paper describes a comprehensive taxonomy of Map Reduce runtimes for different computing environments ranging from traditional homogeneous PC cluster server to dynamic, virtual, heterogeneous, and mobile computing platform, aiming at a good understanding of wide applicability of this model. It also provides a survey for the optimization strategies applied in these runtimes and that are gaining a lot of momentum in both research and industrial communities. The taxonomy and survey is used to identify and expand the fields of application for MapReduce model and provide references for research.

The similarities and differences of essential oil components inAlbum Citri Reticulatae(ACR),Cylindricae Citri Reticulatae (CCR), Folium Citri Reticulatae(FCR), Exocarpium Citri Grandis(ECG),Pericarpium Citri Reticulatae Viride(PCRV) andPericarpium Citri Reticulatae(PCR) were investigated by GC–MS combined with a chemometric method named alternative moving window factor analysis (AMWFA). And temperature‐programmed retention indices (PTRIs) were used together with mass spectra for identification of the essential oil components. In essential oils of ACR, CCR, FCR, ECG, PCRV and PCR, 28, 26, 61, 62, 52 and 48 components were determined representing 93.13, 94.44, 93.53, 87.67, 99.03 and 98.03% of the total relative content, respectively. Also, the essential oils significantly differed both qualitatively and quantitatively. There were 14 common components among ACR, CCR, FCR, ECG, PCRV and PCR, their abundance varied in the ranges from 32.39% in FCR to 94.66% in PCRV. The results obtained may be helpful to the further study of pharmacological activity for their potential utilization as therapeutical agents.

Fully inkjet-printed transparent high-performance thin-film transistors (TFTs) with ultrathin indium tin oxide (ITO) as semiconducting channels were achieved.The energy band alignment at ITO/Al2O3channel/dielectric interface was investigated by in-depth spectroscopy analysis.Fully printed n-type metal–oxide–semiconductor inverters based on ITO TFTs exhibited extremely high gain of 181 at a low-supply voltage of 3 V, promising for applications in advanced electronic devices and circuits.

Background: Medullary thyroid cancer (MTC) has more aggressive behavior and poor prognosis. Ultrasound (US) has facilitated the qualitative diagnosis of thyroid nodules, however, some MTC may be diagnosed as a benign nodule on ultrasound because ultrasound features of malignancy are lacking. The aim of the study was to investigate the association between ultrasound features and biological behavior of MTC. Methods: Ultrasound findings and medical records of patients with MTC between Jan 2015 to Jun 2017 were retrospectively reviewed at Tianjin Medical University Cancer Institute and Hospital. MTC were categorized using modified TI-RADS classification, then were classified as “malignant” (m-MTC) or “US-low-suspicious” (l-MTC). We compared the biological behavior between the two groups, and further analyzed the risk factors for the recurrence. Results: A total of 78 patients were enrolled, of which 55 m-MTC (70.5%) and 23 l-MTC (29.5%) were identified. The N staging of the m-MTC was significantly higher than that of l-MTC(P= 0.000). The preoperative serum Ct level in m-MTC were significantly higher than that of l-MTC(P= 0.035). Biochemical cure were more frequent in l-MTC than that of m-MTC (P= 0.002). Disease recurrence rates were 19.7% (14 of 71). Disease recurrence was more frequent in m-MTC than that of l-MTC (P= 0.013). Disease recurrence was positively associated with extrathyroid extension (P= 0.047), N staging (P= 0.003), preoperative serum Ct level (P= 0.009) and negatively associated with biochemical cure(P= 0.000). In multivariable Cox regression analysis, extrathyroid extension and biochemical cure were independent risk factors for recurrence of MTC. Conclusions: L-MTC has a more indolent character than m-MTC. The extrathyroid extension and biochemical cure were independent risk factors for recurrence of MTC.

We develop a unified hybrid compact model of a different structure β-Ga2O3SBDs for full-wave rectifier and mixer applications. The model results are compared with experimental data, and a good match was attained. Its SPICE-compatibility for circuit simulation is demonstrated in the rectifier and mixer. Considering the universality of this model, it can be practical to characterize β-Ga2O3SBDs with other structures and further evaluate their performance in various circuits.

The health-related functioning of patients with cancer is compromised by several factors, including the disease process, treatment, and the various symptoms that are produced by both disease and treatment. This study was designed to specify the relationship between patients' pain severity and their self-reported quality of life. The study enrolled 216 consecutive consenting adult patients from 2 Chinese cancer centers with pathologically-diagnosed metastatic cancer who could understand and complete the self-report measures. The majority had cancer-related pain and were receiving analgesics. The Chinese version of the Brief Pain Inventory was used to assess the severity and interference of pain. A Chinese translation of the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) was used to assess health-related functional status. Patients' physicians completed a form that indicated characteristics of the patients' cancer, Eastern Cooperative Oncology Group performance status, pain, and current pain treatment. Increasing severity of pain was associated with worsening health-related functioning, even when an estimate of disease severity was taken into account. The correlation between pain severity and impairment was nonlinear. The functional health and well-being of cancer patients with no or mild pain was significantly less impaired than that of patients with moderate or severe pain. The impairment of patients with moderate and severe pain did not differ. Pain severity is an important variable to be taken into account when quality of life outcome measures are considered. The functioning of cancer patients with well-controlled (mild) pain did not differ significantly from that of patients without pain. Providing pain relief should significantly improve the functional status of cancer patients. Cancer 1999;86:1848–55. © 1999 American Cancer Society.

Abstract: Objective: In order to assess the genetic stability of doxorubicin resistance sarcoma S-180R cell linein vivo. Methods: The drug resistant genes and molecules were examined by flow cytometry, Southern blot, Northern blot and RT-PCR. Results: The results showed that drug-efflux in S-180R increased nearly 100-folds, as compared with its parent cells, the rate of half peak width resistant cell/peak high decreased from 0.56 to 0.23 measured by flow cytometry after two years. The mdr1 gene amplified and overexpressed significantly in S-180R and the expression of topoisomerase II α gene decreased remarkably in S-180R. There was no significant different of the MRP expression between S-180R and S-180. Conclusion: These results indicated that drug resistance of S-180R was maintained and also increased. The major mechanism of drug resistance is the amplification and overexpression of mdr1 gene, the decreased expression of topoisomerase II α also contributed to it. So, S-180R is an ideal experimental model for the study of doxorubicin resistance and its reversionin vivo.