Characteristics of N^+ Implanted Layer of 4H-SiC

The nitrogen ions implanted layer of p type 4H SiC epilayer is investigated.The fabrication processes and measurements of the implanted layer are given in details.The profile of implantation depth is simulated using the Monte Carlo simulator TRIM.Lateral Schottky barrier diodes and transfer length method (TLM) measurement structure are made on nitrogen implanted layers for the testing.The concentration of activated donors N d is about 3 0×10 16 cm -3 .The resulting value for the activation rate in this study is 2 percent.The sheet resistance R sh is 30kΩ/□ and the resistivity ρ(R sh × d ) of the implanted layer is 0 72Ω·cm.The electron mobility calculated is about 300cm 2/(V·s) in the N implanted layer.

Investigation on the Luminescent Properties of SiC

Silicon carbide (SiC) is an excellent microelectronic material used to fabricate high frequency, high temperature,high power and non-volatile memory devices.But due to its indirect band gap,SiC based LED cant emit light so efficiently as GaN based LED, so people are eager to seek effective means to improve its luminescence efficiency. Amorphous SiC, porous crystalline SiC, nanometer SiC produced by CVD methods and porous SiC formed by ion implantation are investigated, and great progresses have been gained during the latest few years,which make SiC a promising material for developing OEIC.

A Novel SiC Foam Valve Tray for Distillation Columns

The novel SiC foam valve tray was made of thin slices of SiC foam material with a high specific surfacearea. Hydrodynamic performances of the novel SiC foam valve tray were studied with air-water system at atmos-pheric pressure. These performance parameters included pressure drop, entrainment, weeping and clear liquidheight. The mass transfer efficiency of the SiC foam valve tray was measured in laboratory plate column. Comparedwith the F1 float valve tray, the dry pressure drop was decreased about 25%, the entrainment rate was about 70%lower at high gas load, the weeping was much better, and the mass transfer efficiency was far higher. Thus, theoverall performance of the novel SiC foam valve tray was better than that of F1 float valve tray.

Kinetic and Microstructure of SiC Deposited from SiCl_4-CH_4-H_2

Silicon carbide was prepared from SiCl4-CH4-H2 gaseous precursors by isothermal, isobaric chemical vapor deposition (CVD) at atmospheric pressure and temperatures ranging from 900°C to 1100°C. Kinetic studies showed that carbosilane of SiH2Cl2, SiHCl3 and SiCl2 formed from decomposition of SiCl4 and CH4 contributed to the deposition of hexangular facet and granular pebble structured SiC. An average apparent activation energy of 152 kJ·mol-1 was determined. The overall CVD process was controlled not only by the surface reactions but also by complex gas phase reactions. The as-deposited thin film was characterized using scanning electron microscopy, X-ray diffraction and transmission electron microscopy, these analysis showed that the deposited thin film consisted of pure phase of the β-SiC, the growth morphology of β-SiC differs from hexangular facet to granular pebble struc-tures, which varied with substrate length and CVD temperature.

First Principles Simulation of Molecular Oxygen Adsorption on SiC Nanotubes

We study the binding of molecular oxygen to a （5, 0） single walled SiC nanotube, by means of density functional calculations. The center of a hexagon of silicon and carbon atoms in sites on SiCNT surfaces is the most stable adsorption site for 02 molecule, with a binding energy of -38.22 eV and an average Si-O binding distance of 1.698 A. We have also tested the stability of the 02-adsorbed SiCNT/CNT with ab initio molecular dynamics simulation which have been carried out at room temperature. Furthermore, the adsorption of 02 on the single walled carbon nanotubes has been investigated. Our first-principles calculations predict that the 02 adsorptive capability of silicon carbide nanotubes is much better than that of carbon nanotubes. This might have potential for gas detection and energy storage.

SiC功率器件对未来电力变流器的影响

SiC是一种宽禁带的半导体材料,具有许多优异的物理特性。由于单晶生产技术的进步,开发SiC功率器件已进入具体实施阶段。本文是作者在日本电气学会上的特邀演讲,介绍电力变流器的现状及发展趋势,并预测SiC功率器件对未来电力交流器的影响。

Processing and properties of 2D SiC/SiC composites by precursor infiltration and pyrolysis

Two-dimensional plain-weave silicon carbide fiber fabric reinforced silicon carbide(2D-SiC/SiC)composites were molded by stacking method and densified through precursor infiltration and pyrolysis(PIP)process.SiC coating was deposited as the fiber/matrix interphase layer by chemical vapor deposition(CVD)technique.Fiber/matrix debonding and relatively long fiber pullouts were observed on the fracture surfaces.Additionally,the flexural strength and elastic modulus of the composites with and without fiber/matrix interphase layer were investigated using three-point bending test and single-edge notched beam test.The results show that the fiber fraction and the porosity of 2D-SiC/SiC composites with and without coating are 27.2%(volume fraction)and 11.1%,and 40.7%(volume fraction)and 7.5%,respectively.And the flexural strength and elastic modulus of 2D-SiC/SiC composites with and without coating are 363.3 MPa and 127.8 GPa,and 180.2 MPa and 97.2 GPa,respectively.With a proper thickness,the coating can effectively adjust the fiber/matrix interface,thus causing a dramatic increase in the mechanical properties of the composites.

Effects of SiC amount on phase compositions and properties of Ti_3SiC_2-based composites

The phase compositions and properties of Ti3SiC2-based composites with SiC addition of 5%-30% in mass fraction fabricated by in-situ reaction and hot pressing sintering were studied. SiC addition effectively prevented TiC synthesis but facilitated SiC synthesis. The Ti3SiC2/Ti C-SiC composite had better oxidation resistance when SiC added quantity reached 20% but poorer oxidation resistance with SiC addition under 15% than Ti3SiC2/TiC composite at higher temperatures. There were more than half of the original SiC and a few Ti3SiC2 remaining in Ti3SiC2/Ti C-SiC with 20% SiC addition, but all constituents in Ti3Si2/TiC composite were oxidized after 12 h in air at 1500 °C. The oxidation scale thickness of TS30, 1505.78 μm, was near a half of that of T,2715 μm, at 1500 °C for 20 h. Ti3SiC2/Ti C composite had a flexural strength of 474 MPa, which was surpassed by Ti3SiC2/TiC-SiC composites when SiC added amount reached 15%. The strength reached the peak of 518 MPa at 20% SiC added amount.

Influence of pyrolysis temperature on structure and dielectric properties of polycarbosilane derived silicon carbide ceramic

β-SiC ceramic powders were obtained by pyrolyzing polycarbosilane in vacuum at 800-1200 °C. The β-SiC ceramic powders were characterized by TGA/DSC, XRD and Raman spectroscopy. The dielectric properties of β-SiC ceramic powders were investigated by measuring their complex permittivity by rectangle wave guide method in the frequency range of 8.2-18 GHz. The results show that both real part ε′ and imaginary part ε″ of complex permittivity increase with increasing pyrolysis temperature. The mechanism was proposed that order carbon formed at high temperature resulted in electron relaxation polarization and conductance loss, which contributes to the increase in complex permittivity.

Fabrication of a monolithic 4H-SiC junction barrier schottky diode with the capability of high current

There is a great interest in monolithic 4H-SiC Junction Barrier Schottky （JBS） diodes with the capability of a high forward current for industrial power applications. In this paper, we report large-area monolithic 4H-SiC JBS diodes fabricated on a 10 μm 4H-SiC epitaxial layer doped to 6×1015 cm-3. JBS diodes with an active area of 30 mm2 had a forward current of up to 330 A at a forward voltage of 5 V, which corresponds to a current density of 1100 A/cm2. A near ideal breakdown voltage of 1.6 kV was also achieved for a reverse current of up to 100 gA through the use of an optimum multiple floating guard rings （MFGR） termination, which is about 87.2% of the theoretical value. The differential specific-on resistance （RSP-ON） was meas- ured to be 3.3 mΩcm2, leading to a FOM （VB2/RSP-ON） value of 0.78 GW/cm2, which is very close to the theoretical limit of the tradeoff between the specific-on resistance and breakdown voltage for 4H-SiC unipolar devices.

Fabrication and characterization of graphene derived from SiC

Using novel ideas for the fabrication of epitaxial graphene （EG） on SiC, two forms of graphene termed as vertical aligned gra- phene sheets （VAGS） and graphene covered SiC powder （GCSP） were derived, respectively, from SiC slices and SiC powder, aimed for applications in energy storage and photocatalysis. Herein, the fabrication procedures, morphology characteristics, some intrinsic physical properties and performances for applications in field effect transistor （FET） and cold cathode field emission source are revealed and analyzed based on the graphene materials. The EG on a 2-inch SiC （0001） showed an average sheet resistance about 720 D,/~5 with a non-uniformity 7.2%. The FETs fabricated on the EG possessed a cutoff frequency 80 GHz. Based on the VAGS derived from a completely carbonized SiC slice, a magnetic phase diagram of graphene with irregu- lar zigzag edges is also reported.