Four kinds of SiC fibers with different specific resistivities were prepared by the pyrolysis of cured polycarbosilane fiber. The results show that SiC fibers with different specific resistivities can be obtained by c...Four kinds of SiC fibers with different specific resistivities were prepared by the pyrolysis of cured polycarbosilane fiber. The results show that SiC fibers with different specific resistivities can be obtained by changing the curing and pyrolysis conditions. And the free carbon content and the ability to crystallize no longer affect the specific resistivities notably with the time when the fiber is covered with an excess carbon layer, and the fiber has a low specific resistivity. The excess carbon layer in the circular outer part is originated from the re-pyrolysis and deposition of hydrocarbon volatiles. The removal of the carbon by oxidative treatment may affect the surface property and also promote the magnitude of specific resistivity. The influence of the surface property on the specific resistivity can be considerable and should not be neglected.展开更多
AlGaN-based LEDs with peak wavelength below 240 nm(far-UVC)pose no significant harm to human health,thus highlighting their broader application potential.While,there is a significant Schottky barrier between the n-ele...AlGaN-based LEDs with peak wavelength below 240 nm(far-UVC)pose no significant harm to human health,thus highlighting their broader application potential.While,there is a significant Schottky barrier between the n-electrode and Alrich n-AlGaN,adversely impeding electron injection and resulting in considerable heat generation.Here,we fabricate V-based electrodes of V/Al/Ti/Au on n-AlGaN with Al content over 80%and investigate the relationship between the metal diffusion and contact properties during the high-temperature annealing process.Experiments reveal that decreasing V thickness in the electrode promotes the diffusion of Al towards the surface of n-AlGaN,which facilitates the formation of VN and thus the increase of local electron concentration,resulting in lower specific contact resistivity.Then,increasing the Al thickness inhibits the diffusion of Au to the n-AlGaN surface,suppressing the rise of Schottky barrier.Experimentally,an optimized n-electrode of V(10 nm)/Al(240 nm)/Ti(40 nm)/Au(50 nm)on n-Al_(0.81)Ga_(0.19)N is obtained,realizing an optimal specific contact resistivity of 7.30×10^(−4)Ω·cm^(2).Based on the optimal n-electrode preparation scheme for Al-rich n-AlGaN,the work voltage of a far-UVC LED with peak wavelength of 233.5 nm is effectively reduced.展开更多
Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si...Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si-faced p-type 4H-SiC epilayer. The polysilicon is deposited using low-pressure chemical vapor deposition （LPCVD） and doped by phosphorous ions implantation followed by diffusion to obtain a sheet resistance of 22Ω/□. The specific contact resistance pc of n^＋ polysilicon contact to n-type 4H-SiC as low as 3.82 × 10^-5Ω· cm^2 is achieved. The result for sheet resistance Rsh of the phosphorous ion implanted layers in SiC is about 4.9kΩ/□. The mechanisms for n^＋ polysilicon ohmic contact to n-type SiC are discussed.展开更多
In this paper, a study to enhance the filtration for solid/liquid materials difficult to be filtered, such as highly viscous, highly compactible or gel like materials, is presented. Filter aids diatomaceous earth and ...In this paper, a study to enhance the filtration for solid/liquid materials difficult to be filtered, such as highly viscous, highly compactible or gel like materials, is presented. Filter aids diatomaceous earth and wood pulp cellulose are used to enhance the filtration by improving filter cake structure and properties in the filtration of a biological health product and a highly viscous chemical fiber polymer melt product. The property of solid/liquidsystems, filtration at different flow rates, specitic cake resistance, cake wetness, filtration rate, filtrate turbidity for filter aid selection and evaluation, and operation optimization are investigated. The results are successfully applied to industrial process, .and can be used as a reference for similar filtration applications.展开更多
Specific contact resistance to p-GaN was measured for various structures of Ni/Pd-based metals and thin(20-30 nm thick)p-InGaN/p^(+)-GaN contacting layers.The effects of surface chemical treatment and annealing temper...Specific contact resistance to p-GaN was measured for various structures of Ni/Pd-based metals and thin(20-30 nm thick)p-InGaN/p^(+)-GaN contacting layers.The effects of surface chemical treatment and annealing temperature were ex-amined.The optimal annealing temperature was determined to be 550°C,above which the sheet resistance of the samples de-graded considerably,suggesting that undesirable alloying had occurred.Pd-containing metal showed~35%lower com-pared to that of single Ni.Very thin(2-3.5 nm thick)p-InGaN contacting layers grown on 20-25 nm thick p^(+)-GaN layers exhib-ited one to two orders of magnitude smaller values of compared to that of p^(+)-GaN without p-InGaN.The current density de-pendence of,which is indicative of nonlinearity in current-voltage relation,was also examined.The lowest achieved through this study was 4.9×10^(-5)Ω·cm^(2)@J=3.4 kA/cm^(2).展开更多
Cake filtration has been widely used in many chemical processes with more non-Newtonian, highly viscous and compressible materials involved. Neither traditional nor modem filtration theory can be applied in practice ...Cake filtration has been widely used in many chemical processes with more non-Newtonian, highly viscous and compressible materials involved. Neither traditional nor modem filtration theory can be applied in practice ＂Equivalent cake filtration model＂ is a recently developed mathematical model to describe cake filtration for both Newtonian and non-Newtonian fluids, in either steady or unsteady filtration stages. This model has two strengths： （1） It can be used to determine equivalent capillary radii and predict filtration quality based on the properties of solid/liquid system and operation parameters; and （2） to calculate cake specific resistance and its variations with time at various cake thickness locations.展开更多
The Ti-Al ohmic contact to n-type 6H-SiC has been fabricated. An array of TLM （transfer length method） test patterns with Au/Ti/A1/Ti/SiC structure is formed on N-wells created by P^＋ ion implantation into Si-faced...The Ti-Al ohmic contact to n-type 6H-SiC has been fabricated. An array of TLM （transfer length method） test patterns with Au/Ti/A1/Ti/SiC structure is formed on N-wells created by P^＋ ion implantation into Si-faced p-type 6H-SiC epilayer. The specific contact resistance pc as low as 8.64×10-6Ω·cm^2 is achieved after annealing in N2 at 900℃ for 5min. The sheet resistance Rsh of the implanted layers is 975Ω. X-ray diffraction （XRD） analysis shows the formation of Ti3SiC2 at the metal/n-SiC interface after thermal annealing, which is responsible for the low resistance contact.展开更多
The application of transparent conducting indium-tin-oxide （ITO） film as full front electrode replacing the conven- tional bus-bar metal electrode in III-V compound GalnP solar cell was proposed. A high-quality, non...The application of transparent conducting indium-tin-oxide （ITO） film as full front electrode replacing the conven- tional bus-bar metal electrode in III-V compound GalnP solar cell was proposed. A high-quality, non-rectifying contact between ITO and 10 nm N＋-GaAs contact layer was formed, which is benefiting from a high carrier concentration of the terrilium-doped N＋-GaAs layer, up to 2×10^19 cm^-3. A good device performance of the GalnP solar cell with the ITO electrode was observed. This result indicates a great potential of transparent conducting films in the future fabrication of larger area flexible III-V solar cell.展开更多
A novel super-junction LDMOS with low resistance channel(LRC),named LRC-LDMOS based on the silicon-on-insulator(SOI)technology is proposed.The LRC is highly doped on the surface of the drift region,which can significa...A novel super-junction LDMOS with low resistance channel(LRC),named LRC-LDMOS based on the silicon-on-insulator(SOI)technology is proposed.The LRC is highly doped on the surface of the drift region,which can significantly reduce the specific on resistance(R^(on,sp))in forward conduction.The charge compensation between the LRC,N-pillar,and P-pillar of the super-junction are adjusted to satisfy the charge balance,which can completely deplete the whole drift,thus the breakdown voltage(BV)is enhanced in reverse blocking.The three-dimensional(3D)simulation results show that the BV and R^(on,sp)of the device can reach 253 V and 15.5 mΩ·cm^(2),respectively,and the Baliga's figure of merit(FOM=BV^(2)/R^(on,sp))of 4.1 MW/cm^(2)is achieved,breaking through the silicon limit.展开更多
A novel planar vertical double-diffused metal-oxide-semiconductor （VDMOS） structure with an ultra-low specific on-resistance （Ron,sp）, whose distinctive feature is the use of inhomogeneous floating p-islands in th...A novel planar vertical double-diffused metal-oxide-semiconductor （VDMOS） structure with an ultra-low specific on-resistance （Ron,sp）, whose distinctive feature is the use of inhomogeneous floating p-islands in the n-drift region, is proposed. The theoretical limit of its Ron,sp is deduced, the influence of structure parameters on the breakdown voltage （BV） and Ron,sp are investigated, and the optimized results with BV of 83 V and Ron,sp of 54 mΩ.mm2 are obtained. Simulations show that the inhomogeneous-floating-islands metal-oxide-semiconductor field-effect transistor （MOSFET） has a superior ＂Ron,sp/BV＂ trade-off to the conventional VDMOS （a 38% reduction of Ron,sp with the same BV） and the homogeneous-floating-islands MOSFET （a 10% reduction of Ron,sp with the same BV）. The inhomogeneous-floatingislands MOSFET also has a much better body-diode characteristic than the superjunction MOSFET. Its reverse recovery peak current, reverse recovery time and reverse recovery charge are about 50, 80 and 40% of those of the superjunction MOSFET, respectively.展开更多
The highly-emulsified oily sludge in gas fields is complex in components and serious in emulsification,which makes effective reduction extremely difficult only by a single direct mechanical separation method such as m...The highly-emulsified oily sludge in gas fields is complex in components and serious in emulsification,which makes effective reduction extremely difficult only by a single direct mechanical separation method such as microwave heating,ultrasonic treatment,chemical conditioning,etc.In view of this,this paper presented a new chemical-physical compounding conditioning technology for such highly emulsified oily sludge in gas fields.The experimental samples,from the Mizhi Natural Gas Processing Plant of PetroChina Changqing Oilfield Company,were treated through chemical conditioning,from which the optimal formula,dosages and dosing order were determined.On this basis,the compound technology of chemical-physical conditioning was applied to reduce the specific resistance to filtration(SRF)of the sludge,thus achieving a satisfactory result.The following results were obtained.(1)The chemical conditioning agent with the formula of the oxidant MN-S,calcium oxide and sodium hydroxide was proved to achieve the fastest dewatering speed,and the specific resistance of sludge can be reduced from 130.3 to 3.81 trillion m^(3) per kg.(2)Comparison between microwave and ultrasonic conditioning methods shows that the latter is better in reducing the SRF(the ultrasonic frequency of 40 kHz was applied to reduce the SRF down to 14.01 trillion m^(3) per kg after 4 min of conditioning treatment).(3)The ultrasonic treatment effect after chemical conditioning is the best;the SRF was reduced to 2.77 trillion m^(3) per kg,and the moisture content of the sludge after mechanical dewatering was only 68.71%,decreased by 21.46%compared with the original content of 90.17%.In conclusion,this presented chemical-microwave-ultrasonic compound conditioning technology can reduce the sludge's SRF and the moisture content of filter cakes so as to achieve effective reduction of the highly-emulsified sludge in gas fields.展开更多
This research studies the effect of Mn-Co-La_(2)O_(3) coating synthesized by the electrodeposition method on the oxidation resistance and electrical conductivity of the Crofer 22 APU stainless steel interconnect plate...This research studies the effect of Mn-Co-La_(2)O_(3) coating synthesized by the electrodeposition method on the oxidation resistance and electrical conductivity of the Crofer 22 APU stainless steel interconnect plates in solid oxide fuel cells.The test samples were characterized by a field emission scanning electron microscope(FESEM)equipped with energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The oxidation kinetics of the coated and uncoated samples were studied by tracking their weight changes over time at 800°C,showing that the oxidation mechanism for all samples follows the parabolic law.Lower oxidation rate constant(k_(p))values of the coated sample compared with that of the uncoated one indicated a reduction in the oxidation rate of the steel substrate in the presence of the Mn-Co-La_(2)O_(3) coating.The examination of the cross-section of different samples after the isothermal oxidation for 500 h at 800°C exhibited that applying the composite coating leads to a decrease in the thickness of the chromia layer formed on the steel surface.Furthermore,under these conditions,the area-specific resistance(ASR)of the coated sample(13.11 mΩcm^(2))is significantly lower than that of the uncoated one(41.45 mΩcm^(2)).展开更多
Cu-Mn_(3)O_(4)composite coating was prepared on the SUS 430 ferritic stainless steel by electrodeposition and then exposed in air at 800℃corresponding to the cathode atmosphere of solid oxide fuel cell(SOFC).A dual-l...Cu-Mn_(3)O_(4)composite coating was prepared on the SUS 430 ferritic stainless steel by electrodeposition and then exposed in air at 800℃corresponding to the cathode atmosphere of solid oxide fuel cell(SOFC).A dual-layer oxide structure mainly comprising an external layer of CuO followed by(Cu,Mn,Fe)_(3)O_(4)spinel and an internal layer of Cr-rich oxide was thermally developed on the coated steel.The scale area-specific resistances(ASRs)of the coated steels were lower than the scale ASR of the uncoated steel after identical thermal exposure.The external layer of CuO/(Cu,Mn,Fe)_(3)O_(4)spinel not only served as a barrier to reduce the growth rate of Cr-rich oxide internal layer and to suppress the outward diffusion of Cr,but also lowered the surface scale ASRs considerably.展开更多
This paper reports that highly transparent and low resistance tantalum-doped indium tin oxide （Ta-doped ITO） films contacted to p-type GaN have been prepared by the electron-beam evaporation technique. The Ta-doped ...This paper reports that highly transparent and low resistance tantalum-doped indium tin oxide （Ta-doped ITO） films contacted to p-type GaN have been prepared by the electron-beam evaporation technique. The Ta-doped ITO contacts become Ohmic with a specific contact resistance of $／sim 5.65／times 10^{ - 5}$$／Omega ／cdot$cm$^{2}$ and show the transmittance of $／sim $98% at a wavelength of 440nm when annealed at 500／du. Blue light emitting diodes （LEDs） fabricated with Ta-doped ITO p-type Ohmic contact layers give a forward-bias voltage of 3.21V at an injection current of 20mA. It further shows that the output power of LEDs with Ta-doped ITO contacts is enhanced 62% at 20mA in comparison with that of LEDs with conventional Ni/Au contacts展开更多
Pressure filtration and filter aids should be adopted in filtration of high-viscosity molten chemical fiber containing foreign materials and gel particles. Theoretical analysis and argumentations on manners of assiste...Pressure filtration and filter aids should be adopted in filtration of high-viscosity molten chemical fiber containing foreign materials and gel particles. Theoretical analysis and argumentations on manners of assisted filtration and specific requirements of filter aids are performed. Measurement and comparison on properties of several filter aids are also carried out, conclusions and suggestions are put forward.展开更多
Low-resistance Ohmic contact is critical for the high efficiency GaN-based laser diodes.This study investigates the introduction of the In_(0.15)Ga_(0.85)N contact layer on the specific contact resistance.Experimental...Low-resistance Ohmic contact is critical for the high efficiency GaN-based laser diodes.This study investigates the introduction of the In_(0.15)Ga_(0.85)N contact layer on the specific contact resistance.Experimental results reveal that adopting the In0.15Ga0.85N contact layer yields a minimized specific contact resistance of 2.57×10^(-5)Ω·cm^(2) which is two orders of magnitude lower than the GaN contact layer(7.61×10^(-3)Ω·cm^(2)).A decrease in the specific contact resistance arises from the reduction of the barrier between the metal and p-type In0.15Ga0.85N.To develop an optimal metal electrode combination on the In0.15Ga0.85N contact layer,the Pd/Au and Ni/Au electrode stacks which are most commonly used in the formation of Ohmic contact with p-GaN are investigated.Metal stack of 10/30 nm Pd/Au is demonstrated effective in reducing the specific contact resistance to 10^(-5)Ω·cm^(2) level.The mechanism of the variation of the specific contact resistance under different annealing atmospheres is explained by auger electron spectroscopy.展开更多
The 3C-SiC thin films used herein are grown on Si substrates by chemical vapor deposition. A1 contacts with differ- ent thickness values are deposited on the 3C-SiC/Si （100） structure by the magnetron sputtering met...The 3C-SiC thin films used herein are grown on Si substrates by chemical vapor deposition. A1 contacts with differ- ent thickness values are deposited on the 3C-SiC/Si （100） structure by the magnetron sputtering method and are annealed at different temperatures. We focus on the effects of the annealing temperature on the ohmic contact properties and mi- crostructure of A1/3C-SiC structure. The electrical properties of A1 contacts to n-type 3C-SiC are characterized by the transmission line method. The crystal structures and chemical phases of A1 contacts are examined by X-ray diffraction, Raman spectra, and transmission electron microscopy, respectively. It is found that the A1 contacts exhibit ohmic contact behaviors when the annealing temperature is below 550 ℃, and they become Schottky contacts when the annealing tem- perature is above 650 ℃. A minimum specific contact resistance of 1.8 × 10-4 Ω cm2 is obtained when the A1 contact is annealed at 250 ℃.展开更多
Suction boxes are used in the paper industry to simultaneously drain a pulp suspension and form a fibre mat （or filter cake）. This research addresses the modelling of fibre deposition in the forming unit of an indus...Suction boxes are used in the paper industry to simultaneously drain a pulp suspension and form a fibre mat （or filter cake）. This research addresses the modelling of fibre deposition in the forming unit of an industrial papermachine, assuming a filtration process, and that of the flowing suspension drained through the building fibre mat and the wire on a suction box. From experimental data of the cumulative drained V volume, per unit surface area, for two vacuum pressures △P and 6 dwell times t, an extension of the classical law （t/V） versus V is proposed, validated and applied. This relation enables determining the average specific filtration resistance of the fibre mat over the box and the mass of solids deposited before and over the suction box. The model obtained is as precise as 1% and can be used to limit and reduce the energy consumption of drainage vacuum assisted devices such as suction boxes in the forming unit of industrial papermachines.展开更多
We evaluated the settling ability and dewaterability of granulated methane-oxidizing bacteria （GMOB） after granulation using a continuous-flow reactor. A comparative analysis on settling and dewatering characteristi...We evaluated the settling ability and dewaterability of granulated methane-oxidizing bacteria （GMOB） after granulation using a continuous-flow reactor. A comparative analysis on settling and dewatering characteristics due to changes in sludge retention time （SRT, 10, 15 and 20 days） during cultivation of GMOB was conducted. In assessing dewaterability, the specific resistance to filtration （SRF） of activated sludge and GMOB was found to be 8.21×1013-2.38×1014 and 4.88 × 1012-1.98×1013 m/kg, respectively. It was confirmed that as SRT decreased, SRF of GMOB increased. In the case of bound extracellular polymeric substance （EPS）, activated sludge registered 147.5 mg/g-VSS while GMOB exhibited 171-177.2 mg/g-VSS. In the case of extracellular polymeric substance soluble EPS in effluent, activated sludge measured 62 mg/L and GMOB had 17.4-21.4 mg/L. The particle size analysis showed that mean particle diameters of GMOB were 402, 369, and 350 μm, respectively, at SRTs of 20, 15 and 10 days. In addition, it was found that GMOB had a larger mean particle diameter and exhibited much better settleability and dewaterability than activated sludge did.展开更多
Normal,R0,and anomalous,RS,components of the Hall coefficient are determined from the results of experimental investigations of temperature dependences of the Hall coefficient,magnetic susceptibility,and specific elec...Normal,R0,and anomalous,RS,components of the Hall coefficient are determined from the results of experimental investigations of temperature dependences of the Hall coefficient,magnetic susceptibility,and specific electrical resistance for intermetallic Gd3In,Gd3In5 and GdIn3 compounds.Effective parameters of spin-orbital interactionλSO of intermetallic compounds are calculated from anomalous components RS of the Hall coefficient and specific electrical resistance.The results calculated for the band parameters and effective parameters of spin-orbital interactionλSO for Gd-In system intermetallides coincide by orders of magnitude with the results obtained from the optical spectra of pure REMs(rare-earth metals).展开更多
文摘Four kinds of SiC fibers with different specific resistivities were prepared by the pyrolysis of cured polycarbosilane fiber. The results show that SiC fibers with different specific resistivities can be obtained by changing the curing and pyrolysis conditions. And the free carbon content and the ability to crystallize no longer affect the specific resistivities notably with the time when the fiber is covered with an excess carbon layer, and the fiber has a low specific resistivity. The excess carbon layer in the circular outer part is originated from the re-pyrolysis and deposition of hydrocarbon volatiles. The removal of the carbon by oxidative treatment may affect the surface property and also promote the magnitude of specific resistivity. The influence of the surface property on the specific resistivity can be considerable and should not be neglected.
基金supported by National Key R&D Program of China(2022YFB3605103)National Natural Science Foundation of China(62425408,62121005,U22A2084,12234018)+2 种基金Youth Innovation Promotion Association of the Chinese Academy of Sciences(2023223)Natural Science Foundation of Jilin Province(20230101345JC,20230101360JC,SKL202302026)Young Elite Scientist Sponsorship Program by CAST(YESS20200182).
文摘AlGaN-based LEDs with peak wavelength below 240 nm(far-UVC)pose no significant harm to human health,thus highlighting their broader application potential.While,there is a significant Schottky barrier between the n-electrode and Alrich n-AlGaN,adversely impeding electron injection and resulting in considerable heat generation.Here,we fabricate V-based electrodes of V/Al/Ti/Au on n-AlGaN with Al content over 80%and investigate the relationship between the metal diffusion and contact properties during the high-temperature annealing process.Experiments reveal that decreasing V thickness in the electrode promotes the diffusion of Al towards the surface of n-AlGaN,which facilitates the formation of VN and thus the increase of local electron concentration,resulting in lower specific contact resistivity.Then,increasing the Al thickness inhibits the diffusion of Au to the n-AlGaN surface,suppressing the rise of Schottky barrier.Experimentally,an optimized n-electrode of V(10 nm)/Al(240 nm)/Ti(40 nm)/Au(50 nm)on n-Al_(0.81)Ga_(0.19)N is obtained,realizing an optimal specific contact resistivity of 7.30×10^(−4)Ω·cm^(2).Based on the optimal n-electrode preparation scheme for Al-rich n-AlGaN,the work voltage of a far-UVC LED with peak wavelength of 233.5 nm is effectively reduced.
文摘Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si-faced p-type 4H-SiC epilayer. The polysilicon is deposited using low-pressure chemical vapor deposition （LPCVD） and doped by phosphorous ions implantation followed by diffusion to obtain a sheet resistance of 22Ω/□. The specific contact resistance pc of n^＋ polysilicon contact to n-type 4H-SiC as low as 3.82 × 10^-5Ω· cm^2 is achieved. The result for sheet resistance Rsh of the phosphorous ion implanted layers in SiC is about 4.9kΩ/□. The mechanisms for n^＋ polysilicon ohmic contact to n-type SiC are discussed.
文摘In this paper, a study to enhance the filtration for solid/liquid materials difficult to be filtered, such as highly viscous, highly compactible or gel like materials, is presented. Filter aids diatomaceous earth and wood pulp cellulose are used to enhance the filtration by improving filter cake structure and properties in the filtration of a biological health product and a highly viscous chemical fiber polymer melt product. The property of solid/liquidsystems, filtration at different flow rates, specitic cake resistance, cake wetness, filtration rate, filtrate turbidity for filter aid selection and evaluation, and operation optimization are investigated. The results are successfully applied to industrial process, .and can be used as a reference for similar filtration applications.
基金the National Key Research and Development Program of China(2017YFE0131500)the Key Research and Development Program of Guangdong Province(2020B090922001)+2 种基金National Natural Science Foundation of China(61834008)Key Research and Development Program of Jiangsu province(BE2020004,BE2021008-1)Guangdong Basic and Applied Basic Research Foundation(2019B1515120091).
文摘Specific contact resistance to p-GaN was measured for various structures of Ni/Pd-based metals and thin(20-30 nm thick)p-InGaN/p^(+)-GaN contacting layers.The effects of surface chemical treatment and annealing temperature were ex-amined.The optimal annealing temperature was determined to be 550°C,above which the sheet resistance of the samples de-graded considerably,suggesting that undesirable alloying had occurred.Pd-containing metal showed~35%lower com-pared to that of single Ni.Very thin(2-3.5 nm thick)p-InGaN contacting layers grown on 20-25 nm thick p^(+)-GaN layers exhib-ited one to two orders of magnitude smaller values of compared to that of p^(+)-GaN without p-InGaN.The current density de-pendence of,which is indicative of nonlinearity in current-voltage relation,was also examined.The lowest achieved through this study was 4.9×10^(-5)Ω·cm^(2)@J=3.4 kA/cm^(2).
文摘Cake filtration has been widely used in many chemical processes with more non-Newtonian, highly viscous and compressible materials involved. Neither traditional nor modem filtration theory can be applied in practice ＂Equivalent cake filtration model＂ is a recently developed mathematical model to describe cake filtration for both Newtonian and non-Newtonian fluids, in either steady or unsteady filtration stages. This model has two strengths： （1） It can be used to determine equivalent capillary radii and predict filtration quality based on the properties of solid/liquid system and operation parameters; and （2） to calculate cake specific resistance and its variations with time at various cake thickness locations.
基金Project supported by the National Basic Research Program of China （Grant No 2002CB311904）, the National Defense Basic Research Program of China （Grant No 51327010101） and the National Natural Science Foundation of China （Grant No 60376001）.
文摘The Ti-Al ohmic contact to n-type 6H-SiC has been fabricated. An array of TLM （transfer length method） test patterns with Au/Ti/A1/Ti/SiC structure is formed on N-wells created by P^＋ ion implantation into Si-faced p-type 6H-SiC epilayer. The specific contact resistance pc as low as 8.64×10-6Ω·cm^2 is achieved after annealing in N2 at 900℃ for 5min. The sheet resistance Rsh of the implanted layers is 975Ω. X-ray diffraction （XRD） analysis shows the formation of Ti3SiC2 at the metal/n-SiC interface after thermal annealing, which is responsible for the low resistance contact.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61534008,61376081,and 61404157)the Application Foundation of Suzhou,China(Grant No.SYG201437)
文摘The application of transparent conducting indium-tin-oxide （ITO） film as full front electrode replacing the conven- tional bus-bar metal electrode in III-V compound GalnP solar cell was proposed. A high-quality, non-rectifying contact between ITO and 10 nm N＋-GaAs contact layer was formed, which is benefiting from a high carrier concentration of the terrilium-doped N＋-GaAs layer, up to 2×10^19 cm^-3. A good device performance of the GalnP solar cell with the ITO electrode was observed. This result indicates a great potential of transparent conducting films in the future fabrication of larger area flexible III-V solar cell.
文摘A novel super-junction LDMOS with low resistance channel(LRC),named LRC-LDMOS based on the silicon-on-insulator(SOI)technology is proposed.The LRC is highly doped on the surface of the drift region,which can significantly reduce the specific on resistance(R^(on,sp))in forward conduction.The charge compensation between the LRC,N-pillar,and P-pillar of the super-junction are adjusted to satisfy the charge balance,which can completely deplete the whole drift,thus the breakdown voltage(BV)is enhanced in reverse blocking.The three-dimensional(3D)simulation results show that the BV and R^(on,sp)of the device can reach 253 V and 15.5 mΩ·cm^(2),respectively,and the Baliga's figure of merit(FOM=BV^(2)/R^(on,sp))of 4.1 MW/cm^(2)is achieved,breaking through the silicon limit.
基金Project supported by the National Key Scientific and Technological Project (Grant No. 2011ZX02503-005)the Fundamental Research Funds for the Central Universities (Grant No. ZYGX2010J038)
文摘A novel planar vertical double-diffused metal-oxide-semiconductor （VDMOS） structure with an ultra-low specific on-resistance （Ron,sp）, whose distinctive feature is the use of inhomogeneous floating p-islands in the n-drift region, is proposed. The theoretical limit of its Ron,sp is deduced, the influence of structure parameters on the breakdown voltage （BV） and Ron,sp are investigated, and the optimized results with BV of 83 V and Ron,sp of 54 mΩ.mm2 are obtained. Simulations show that the inhomogeneous-floating-islands metal-oxide-semiconductor field-effect transistor （MOSFET） has a superior ＂Ron,sp/BV＂ trade-off to the conventional VDMOS （a 38% reduction of Ron,sp with the same BV） and the homogeneous-floating-islands MOSFET （a 10% reduction of Ron,sp with the same BV）. The inhomogeneous-floatingislands MOSFET also has a much better body-diode characteristic than the superjunction MOSFET. Its reverse recovery peak current, reverse recovery time and reverse recovery charge are about 50, 80 and 40% of those of the superjunction MOSFET, respectively.
基金supported by the National Natural Science Foundation of China“Study on Wellbore Damage Instability Based on Configuration Mechanics Theory”(No.:51674200)the Technical Research Project of PetroChina Changqing Oilfield Company“Analysis and Countermeasure Study of Produced Water Treatment System of the Mizhi Natural Gas Processing Plant in 2017”(No.:GXTC-CZ-1757181).
文摘The highly-emulsified oily sludge in gas fields is complex in components and serious in emulsification,which makes effective reduction extremely difficult only by a single direct mechanical separation method such as microwave heating,ultrasonic treatment,chemical conditioning,etc.In view of this,this paper presented a new chemical-physical compounding conditioning technology for such highly emulsified oily sludge in gas fields.The experimental samples,from the Mizhi Natural Gas Processing Plant of PetroChina Changqing Oilfield Company,were treated through chemical conditioning,from which the optimal formula,dosages and dosing order were determined.On this basis,the compound technology of chemical-physical conditioning was applied to reduce the specific resistance to filtration(SRF)of the sludge,thus achieving a satisfactory result.The following results were obtained.(1)The chemical conditioning agent with the formula of the oxidant MN-S,calcium oxide and sodium hydroxide was proved to achieve the fastest dewatering speed,and the specific resistance of sludge can be reduced from 130.3 to 3.81 trillion m^(3) per kg.(2)Comparison between microwave and ultrasonic conditioning methods shows that the latter is better in reducing the SRF(the ultrasonic frequency of 40 kHz was applied to reduce the SRF down to 14.01 trillion m^(3) per kg after 4 min of conditioning treatment).(3)The ultrasonic treatment effect after chemical conditioning is the best;the SRF was reduced to 2.77 trillion m^(3) per kg,and the moisture content of the sludge after mechanical dewatering was only 68.71%,decreased by 21.46%compared with the original content of 90.17%.In conclusion,this presented chemical-microwave-ultrasonic compound conditioning technology can reduce the sludge's SRF and the moisture content of filter cakes so as to achieve effective reduction of the highly-emulsified sludge in gas fields.
文摘This research studies the effect of Mn-Co-La_(2)O_(3) coating synthesized by the electrodeposition method on the oxidation resistance and electrical conductivity of the Crofer 22 APU stainless steel interconnect plates in solid oxide fuel cells.The test samples were characterized by a field emission scanning electron microscope(FESEM)equipped with energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The oxidation kinetics of the coated and uncoated samples were studied by tracking their weight changes over time at 800°C,showing that the oxidation mechanism for all samples follows the parabolic law.Lower oxidation rate constant(k_(p))values of the coated sample compared with that of the uncoated one indicated a reduction in the oxidation rate of the steel substrate in the presence of the Mn-Co-La_(2)O_(3) coating.The examination of the cross-section of different samples after the isothermal oxidation for 500 h at 800°C exhibited that applying the composite coating leads to a decrease in the thickness of the chromia layer formed on the steel surface.Furthermore,under these conditions,the area-specific resistance(ASR)of the coated sample(13.11 mΩcm^(2))is significantly lower than that of the uncoated one(41.45 mΩcm^(2)).
基金Funded by the Youth Science and Technology Talent Growth Project of Education Department of Guizhou Province(No.KY[2018]145)。
文摘Cu-Mn_(3)O_(4)composite coating was prepared on the SUS 430 ferritic stainless steel by electrodeposition and then exposed in air at 800℃corresponding to the cathode atmosphere of solid oxide fuel cell(SOFC).A dual-layer oxide structure mainly comprising an external layer of CuO followed by(Cu,Mn,Fe)_(3)O_(4)spinel and an internal layer of Cr-rich oxide was thermally developed on the coated steel.The scale area-specific resistances(ASRs)of the coated steels were lower than the scale ASR of the uncoated steel after identical thermal exposure.The external layer of CuO/(Cu,Mn,Fe)_(3)O_(4)spinel not only served as a barrier to reduce the growth rate of Cr-rich oxide internal layer and to suppress the outward diffusion of Cr,but also lowered the surface scale ASRs considerably.
基金Project supported by Science and Technology Planning Project of Guangdong Province (Grant No. 2007A010501008)the Production and Research Project of Guangdong Province and the Ministry of Education (Grant No. 2009B090300338)
文摘This paper reports that highly transparent and low resistance tantalum-doped indium tin oxide （Ta-doped ITO） films contacted to p-type GaN have been prepared by the electron-beam evaporation technique. The Ta-doped ITO contacts become Ohmic with a specific contact resistance of $／sim 5.65／times 10^{ - 5}$$／Omega ／cdot$cm$^{2}$ and show the transmittance of $／sim $98% at a wavelength of 440nm when annealed at 500／du. Blue light emitting diodes （LEDs） fabricated with Ta-doped ITO p-type Ohmic contact layers give a forward-bias voltage of 3.21V at an injection current of 20mA. It further shows that the output power of LEDs with Ta-doped ITO contacts is enhanced 62% at 20mA in comparison with that of LEDs with conventional Ni/Au contacts
文摘Pressure filtration and filter aids should be adopted in filtration of high-viscosity molten chemical fiber containing foreign materials and gel particles. Theoretical analysis and argumentations on manners of assisted filtration and specific requirements of filter aids are performed. Measurement and comparison on properties of several filter aids are also carried out, conclusions and suggestions are put forward.
基金funded by the Natural Science Foundation of China Project,grant number 62274042Natural Science Foundation of Shanghai,grant number 21ZR1406200the Key Research and Development Program of Jiangsu Province,grant number BE2021008-5.
文摘Low-resistance Ohmic contact is critical for the high efficiency GaN-based laser diodes.This study investigates the introduction of the In_(0.15)Ga_(0.85)N contact layer on the specific contact resistance.Experimental results reveal that adopting the In0.15Ga0.85N contact layer yields a minimized specific contact resistance of 2.57×10^(-5)Ω·cm^(2) which is two orders of magnitude lower than the GaN contact layer(7.61×10^(-3)Ω·cm^(2)).A decrease in the specific contact resistance arises from the reduction of the barrier between the metal and p-type In0.15Ga0.85N.To develop an optimal metal electrode combination on the In0.15Ga0.85N contact layer,the Pd/Au and Ni/Au electrode stacks which are most commonly used in the formation of Ohmic contact with p-GaN are investigated.Metal stack of 10/30 nm Pd/Au is demonstrated effective in reducing the specific contact resistance to 10^(-5)Ω·cm^(2) level.The mechanism of the variation of the specific contact resistance under different annealing atmospheres is explained by auger electron spectroscopy.
基金supported by the Shanghai Rising-Star Program,China(Grant No.13QA1403800)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.51002176)+2 种基金the Innovation Program of the Chinese Academy of Sciences(Grant No.KJCX2-EW-W10)the Industry–Academic Joint Technological Innovations Fund Project of Jiangsu Province,China(Grant No.BY2011119)the National High Technology Research and Development Program of China(Grant Nos.2013AA031603 and 2014AA032602)
文摘The 3C-SiC thin films used herein are grown on Si substrates by chemical vapor deposition. A1 contacts with differ- ent thickness values are deposited on the 3C-SiC/Si （100） structure by the magnetron sputtering method and are annealed at different temperatures. We focus on the effects of the annealing temperature on the ohmic contact properties and mi- crostructure of A1/3C-SiC structure. The electrical properties of A1 contacts to n-type 3C-SiC are characterized by the transmission line method. The crystal structures and chemical phases of A1 contacts are examined by X-ray diffraction, Raman spectra, and transmission electron microscopy, respectively. It is found that the A1 contacts exhibit ohmic contact behaviors when the annealing temperature is below 550 ℃, and they become Schottky contacts when the annealing tem- perature is above 650 ℃. A minimum specific contact resistance of 1.8 × 10-4 Ω cm2 is obtained when the A1 contact is annealed at 250 ℃.
文摘Suction boxes are used in the paper industry to simultaneously drain a pulp suspension and form a fibre mat （or filter cake）. This research addresses the modelling of fibre deposition in the forming unit of an industrial papermachine, assuming a filtration process, and that of the flowing suspension drained through the building fibre mat and the wire on a suction box. From experimental data of the cumulative drained V volume, per unit surface area, for two vacuum pressures △P and 6 dwell times t, an extension of the classical law （t/V） versus V is proposed, validated and applied. This relation enables determining the average specific filtration resistance of the fibre mat over the box and the mass of solids deposited before and over the suction box. The model obtained is as precise as 1% and can be used to limit and reduce the energy consumption of drainage vacuum assisted devices such as suction boxes in the forming unit of industrial papermachines.
基金supported by a grant from a strategic research project (2012-0133-01) funded by the Korea Institute of Construction Technology
文摘We evaluated the settling ability and dewaterability of granulated methane-oxidizing bacteria （GMOB） after granulation using a continuous-flow reactor. A comparative analysis on settling and dewatering characteristics due to changes in sludge retention time （SRT, 10, 15 and 20 days） during cultivation of GMOB was conducted. In assessing dewaterability, the specific resistance to filtration （SRF） of activated sludge and GMOB was found to be 8.21×1013-2.38×1014 and 4.88 × 1012-1.98×1013 m/kg, respectively. It was confirmed that as SRT decreased, SRF of GMOB increased. In the case of bound extracellular polymeric substance （EPS）, activated sludge registered 147.5 mg/g-VSS while GMOB exhibited 171-177.2 mg/g-VSS. In the case of extracellular polymeric substance soluble EPS in effluent, activated sludge measured 62 mg/L and GMOB had 17.4-21.4 mg/L. The particle size analysis showed that mean particle diameters of GMOB were 402, 369, and 350 μm, respectively, at SRTs of 20, 15 and 10 days. In addition, it was found that GMOB had a larger mean particle diameter and exhibited much better settleability and dewaterability than activated sludge did.
文摘Normal,R0,and anomalous,RS,components of the Hall coefficient are determined from the results of experimental investigations of temperature dependences of the Hall coefficient,magnetic susceptibility,and specific electrical resistance for intermetallic Gd3In,Gd3In5 and GdIn3 compounds.Effective parameters of spin-orbital interactionλSO of intermetallic compounds are calculated from anomalous components RS of the Hall coefficient and specific electrical resistance.The results calculated for the band parameters and effective parameters of spin-orbital interactionλSO for Gd-In system intermetallides coincide by orders of magnitude with the results obtained from the optical spectra of pure REMs(rare-earth metals).
