Pristine graphene supported ultrasmall, highly dispersed, and high-density Co–W–P nanoparticles were synthesized via phosphotungstic-acid-mediated self-assembly, showing superior HER catalytic performance.

The transient electromagnetic method (TEM) has a wide range of applications in the hydrogeological exploration mining engineering. This is highly sensitive to groundwater responses and provides reliable data for prevention water-related disasters, such as sudden water surges gushes. However, there are currently lack comprehensive systematic analyses summaries regarding characteristics magnetic source coil devices. Based on fixed field source, this paper categorizes devices into fixed-source...

As-doped p-type ZnO films were grown on GaAs by sputtering and thermal diffusion process. Hall effect measurements showed that the as-grown of n-type conductivity they converted to behavior after annealing. Moreover, hole concentration was very impressible oxygen ambient applied during annealing In addition, bonding state As in investigated x-ray photoelectron spectroscopy. This study not only demonstrated an effective method for reliable reproducible fabrication but also helped understand...

An improved Bosch etching process using inductively coupled plasma system has been investigated for the of 4H-silicon carbide (SiC). By optimizing etch parameters, a mesa structure with nearly vertical sidewall and without microtrench at bottom corner fabricated, formation elimination are preliminarily discussed cycles in this paper. Scanning electron microscopic analysis was used to demonstrate etched morphology under different conditions. Simple mesa-terminated 4H-SiC p-i-n diodes were...

Abstract A new ultralow gate–drain charge ( Q GD ) 4H-SiC trench MOSFET is presented and its mechanism investigated by simulation. The novel features double shielding structures (DS-MOS): one the grounded split gate (SG), other P + region (PSR). Both SG PSR reduce coupling effect between drain, transform most part of capacitance C into gate–source GS drain–source DS in series. Thus reduced proposed DS-MOS obtains . Compared with double-trench (DT-MOS) conventional (CT-MOS), decreases 85%...

The insulated-gate bipolar transistor (IGBT) has a parasitic thyristor. Latch-up can occur when the current density exceeds particular density. Conventional methods employed to increase latching will lead some other performance degradations. To overcome these problems and further of IGBT, novel IGBT with floating N-doped buried layer in P-base is proposed. By implanting P-base, hole flowing underneath N+ emitter be reduced significantly. Thus, that needed trigger latch-up thyristor...

Homoepitaxial growth of 4H-SiC epilayers is conducted in a SiH4-C2H4-H2 system by low pressure hot-wall vertical chemical vapor deposition (CVD). Thick 45 μm are achieved at high rate up to 26 μm/h under an optimized condition, and characterized using Normaski optical microscope, scanning electronic microscope (SEM), atomic force (AFM) x-ray diffractometer (XRD), indicating good crystalline quality with mirror-like smooth surfaces rms roughness 0.9 nm 5 × 5μm area. The dependence the on...

Abstract A novel 4H-SiC trench MOSFET is presented and investigated by simulation in this paper. The device features an integrated Schottky barrier diode L-shaped P + shielding region beneath the gate aside one wall of (S-TMOS). works as a free-wheeling reverse recovery conduction, which significantly reduces charge ( Q rr ) turn-on voltage V F ). effectively shields coupling drain, resulting lower gate–drain capacitance C gd date–drain Compared with that conventional SiC (C-TMOS), S-TMOS...

An optimized linearly graded field limiting ring (LG-FLR) termination structure for high voltage power 4H-SiC diodes has been presented in this paper. Simulated designs were performed to investigate SiC termination, and determine the optimum guard spacing planar diodes. results show that LG-FLR provides a smooth uniform surface electric distribution without spikes. In addition, consumes smaller length than conventional FLR structures. Implanted JBS with fabricated correlated simulation....

The vacancy-enhanced rapid diffusion of N-type dopants especially phosphorus has been a hurdle for the development germanium based complementary metal-oxide-semiconductor (CMOS) technology. Phosphorus diffuses quickly in via formation Phosphorus-Vacancy (P-V) pairs. Trapping vacancies thus slowing down P by some elements like carbon, nitrogen and fluorine proved to be effective. In this work, junction control carbon co-implantation pre-amorphized is investigated systematically. It found that...

Silicon carbide (SiC) devices have attracted much attention due to their superior characteristics of high blocking voltage, frequency and operating temperature. In recent years, with the continuous development SiC device technology, domestic foreign high-voltage made certain breakthroughs. this paper, a 6.5kV/400A module is prepared using 6.5kV MOSFET chip SBD independently developed by research group. The on-resistance 20.8mΩ at junction temperature 150°C, drain leakage current 146μA under...

The Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) team is developing the Giant Steerable Science Mirror (GSSM) for Thirty Meter Telescope (TMT) which will get into preliminary design phase in 2016. To develop passive support structure system largest elliptic-plan flat mirror smoothest tracking mechanism gravity-invariant condition, CIOMP designing building a 1/4 scale, functionally accurate version GSSM prototype. prototype incorporate same optical-mechanical electric...

Decreasing the chip thickness of insulated gate bipolar transistor (IGBT) to improve performance makes current crowding effect become more pronounced during short-circuit turn-off, especially in self-clamping mode (SCM). Former researchers have investigated failure mechanisms turn-off. But measures further robustness IGBT turn-off and simultaneously still need investigations. This paper focuses on influences major device parameters SCM, its tradeoff characteristics with via symmetrical...

This paper investigates the influences of various topside cell structures insulated gate bipolar transistor (IGBT) on current crowding effect during high turn-OFF by symmetrical multicell numerical simulations. It is observed that lower breakdown electric field in drift region can reduce negative differential resistance forward blocking curve and therefore suppress turn-OFF. We refer to this characteristic as self-suppressing (SSCCE). Different IGBT have considerable influence SSCCE. A...

We have successfully developed 6500V SiC MOSFET on 6-inch wafer with the on-resistance of 160mΩ and specific 55mΩ.cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . In this paper, simulation, fabrication electrical characteristic are reported. At same time, some body diode characteristics revealed. Experiments simulations show that when Vgs=0V p-well surface doping concentration affects conduction characteristics. The current mainly...

We study a series of (HfO2)x(Al2O3)1 − x /4H-SiC MOS capacitors. It is shown that the conduction band offset HfO2 0.5 eV and HfAlO 1.11–1.72 eV. The offsets are increased with increase Al composition, offer acceptable barrier heights (> 1 eV) for both electrons holes. With higher offset, x/4H-SiC capacitors result in ∼ 3 orders magnitude lower gate leakage current at an effective electric field 15 MV/cm roughly same breakdown 25 compared to HfO2. Considering tradeoff among gap, dielectric...

Chloride-based fast homoepitaxial growth of 4H-SiC epilayers was performed on 4° off-axis substrates in a home-made vertical hot-wall chemical vapor deposition (CVD) system using H2−SiH4−C2H4−HCl. The effect the SiH4/H2 ratio and reactor pressure rate has been studied successively. increase proportion to influence mechanism chlorine investigated. With increasing from 40 100 Torr, increased 52 μm/hand then decreased 47 μm/h, which is due joint H2 HCl etching as well formation Si clusters at...

Compared with silicon power devices, SiC devices have attracted much attention due to their advantages in high voltage, frequency, and operating temperature. With the continuous improvement of voltage level switching speed MOSFET a higher transient electric field will be generated, during turn-on turn-off process device. When semiconductor device dynamic test system is used evaluate characteristics, distributed capacitance circuit introduce an additional current difference under field,...