An improved 4H-SiC metal-semiconductor field-effect transistors （MESFETs） with step p-buffer layer is proposed, and the static and dynamic electrical performances are analysed in this paper. A step p-buffer layer ha...An improved 4H-SiC metal-semiconductor field-effect transistors （MESFETs） with step p-buffer layer is proposed, and the static and dynamic electrical performances are analysed in this paper. A step p-buffer layer has been applied not only to increase the channel current, but also to improve the transconductance. This is due to the fact that the variation in p-buffer layer depth leads to the decrease in parasitic series resistance resulting from the change in the active channel thickness and modulation in the electric field distribution inside the channel. Detailed numerical simulations demonstrate that the saturation drain current and the maximum theoretical output power density of the proposed structure are about 30% and 37% larger than those of the conventional structure. The cut-off frequency and the maximum oscillation frequency of the proposed MESFETs are 14.5 and 62 GHz, respectively, which are higher than that of the conventional structure. Therefore, the 4H-SiC MESFETs with step p-buffer layer have superior direct-current and radio-frequency performances compared to the similar devices based on the conventional structure.展开更多
Sub-threshold characteristics of the dual material gate 4H-SiC MESFET （DMGFET） are investigated and the analytical models to describe the drain-induced barrier lowering （DIBL） effect are derived by solving one- an...Sub-threshold characteristics of the dual material gate 4H-SiC MESFET （DMGFET） are investigated and the analytical models to describe the drain-induced barrier lowering （DIBL） effect are derived by solving one- and two- dimensional Poisson＇s equations. Using these models, we calculate the bottom potential of the channel and the threshold voltage shift, which characterize the drain-induced barrier lowering （DIBL） effect. The calculated results reveal that the dual material gate （DMG） structure alleviates the deterioration of the threshold voltage and thus suppresses the DIBL effect due to the introduced step function, which originates from the work function difference of the two gate materials when compared with the conventional single material gate metal-semiconductor field-effect transistor （SMGFET）.展开更多
A metal-semiconductor composite with the interracial shells is investigated theoretically for the large linear mag- netoresistance effect of high doping Ag2＋δ Se and Ag2＋δ te materials. The magnetoresistance （MR...A metal-semiconductor composite with the interracial shells is investigated theoretically for the large linear mag- netoresistance effect of high doping Ag2＋δ Se and Ag2＋δ te materials. The magnetoresistance （MR） of composites is a function of the magnetic field, temperature, the conductivities of two phases without magnetic field, and the thickness and conductivity of the interracial shells. The MR increases with the increase of the magnetic field and with the decrease of temperature, and no saturation is found even under the high magnetic field. Moreover, it is interestingly found that the interracial shell is an important factor for the MR of the composites. The MR increases with the thickness and the conductivity of the interfacial shells. Lastly, the theoretical results on the MR are compared with the experimental data. It is found that the value of the MR of the composite with the interfacial shell is larger than that without the interfacial shell.展开更多
A complete model of Metal-Semiconductor-Metal Photodetector(MSM-PD) is presented. It can be used in any circuit simulators. Simulated DC characteristics for a GaAs MSM-PD are in good agreement with reported results.
Variable-energy positron annihilation spectroscopy has been applied to study interfaces in Al/Si, Au/Si and Au/GaAs structures. Computational fittings of ROYPROF program were used to analyze Doppler broadening results...Variable-energy positron annihilation spectroscopy has been applied to study interfaces in Al/Si, Au/Si and Au/GaAs structures. Computational fittings of ROYPROF program were used to analyze Doppler broadening results in order to determine kinds of regions that positrons were likely to sample. The interfaces were found acting as a capturing thin layer with negligible positrons stopped in them and their characteristics came only from positrons diffusing to these interfaces, the positron work function of these materials were taken into consideration. In all fittings, the interfaces are found to have 1 nm thickness and act as an absorbing sink for all thermal positrons diffusing towards them, and this indicates either the existence of open volume defects or a weakness of known theoretical models for positron affinities. The result is supported by measurements obtained by applying external electric fields on Al/Si sample. Theoretical fittings have clearly demonstrated the sensitivity of interfaces in these attempts and their importance in data analyzing and in developing of fitting cods.展开更多
Emerging engineering strategies of colloidal metal-semiconductor nanorod hybrid nanostructures spanning from type,size,dimension,and location of both metal nanoparticles and semiconductors,co-catalyst,band gap structu...Emerging engineering strategies of colloidal metal-semiconductor nanorod hybrid nanostructures spanning from type,size,dimension,and location of both metal nanoparticles and semiconductors,co-catalyst,band gap structure,surface ligand to hole scavenger are elaborated symmetrically to rationalize the design of this type of intriguing materials for efficient photocatalytic applications.展开更多
SiC MOSFET因其高击穿电压、高开关速度、低导通损耗等性能优势而被广泛应用于各类电力电子变换器中。然而,由于其短路耐受时间仅为2~7μs,且随母线电压升高而缩短,快速可靠的短路保护电路已成为其推广应用的关键技术之一。为应对不同...SiC MOSFET因其高击穿电压、高开关速度、低导通损耗等性能优势而被广泛应用于各类电力电子变换器中。然而,由于其短路耐受时间仅为2~7μs,且随母线电压升高而缩短,快速可靠的短路保护电路已成为其推广应用的关键技术之一。为应对不同母线电压下的Si C MOSFET短路故障,文中提出一种基于漏源电压积分的自适应快速短路保护方法(drain-sourcevoltageintegration-basedadaptivefast short-circuit protection method,DSVI-AFSCPM),研究所提出的DSVI-AFSCPM在硬开关短路(hardswitchingfault,HSF)和负载短路(fault under load,FUL)条件下的保护性能,进而研究不同母线电压对DSVI-AFSCPM的作用机理。同时,探究Si CMOSFET工作温度对其响应速度的影响。最后,搭建实验平台,对所提出的DSVI-AFSCPM在发生硬开关短路和负载短路时不同母线电压、不同工作温度下的保护性能进行实验测试。实验结果表明,所提出的DSVI-AFSCPM在不同母线电压下具有良好的保护速度自适应性,即母线电压越高,短路保护速度越快,并且其响应速度受Si CMOSFET工作温度影响较小,两种短路工况下工作温度从25℃变化到125℃,短路保护时间变化不超过90 ns。因此,该文为Si CMOSFET在不同母线电压下的可靠使用提供一定技术支撑。展开更多
基金Project supported by the Fundamental Research Funds for the Central Universities(Grant No.ZYGX2009J029)
文摘An improved 4H-SiC metal-semiconductor field-effect transistors （MESFETs） with step p-buffer layer is proposed, and the static and dynamic electrical performances are analysed in this paper. A step p-buffer layer has been applied not only to increase the channel current, but also to improve the transconductance. This is due to the fact that the variation in p-buffer layer depth leads to the decrease in parasitic series resistance resulting from the change in the active channel thickness and modulation in the electric field distribution inside the channel. Detailed numerical simulations demonstrate that the saturation drain current and the maximum theoretical output power density of the proposed structure are about 30% and 37% larger than those of the conventional structure. The cut-off frequency and the maximum oscillation frequency of the proposed MESFETs are 14.5 and 62 GHz, respectively, which are higher than that of the conventional structure. Therefore, the 4H-SiC MESFETs with step p-buffer layer have superior direct-current and radio-frequency performances compared to the similar devices based on the conventional structure.
基金Project supported by the Pre-research Foundation from the National Ministries and Commissions of China (GrantNo.51308030201)
文摘Sub-threshold characteristics of the dual material gate 4H-SiC MESFET （DMGFET） are investigated and the analytical models to describe the drain-induced barrier lowering （DIBL） effect are derived by solving one- and two- dimensional Poisson＇s equations. Using these models, we calculate the bottom potential of the channel and the threshold voltage shift, which characterize the drain-induced barrier lowering （DIBL） effect. The calculated results reveal that the dual material gate （DMG） structure alleviates the deterioration of the threshold voltage and thus suppresses the DIBL effect due to the introduced step function, which originates from the work function difference of the two gate materials when compared with the conventional single material gate metal-semiconductor field-effect transistor （SMGFET）.
基金Supported by the China Postdoctoral Science Foundation under Grant No 2014MM551868the Science and Technology Development Guidance Program of Qingdao under Grant No KJZD-13-35-JCH
文摘A metal-semiconductor composite with the interracial shells is investigated theoretically for the large linear mag- netoresistance effect of high doping Ag2＋δ Se and Ag2＋δ te materials. The magnetoresistance （MR） of composites is a function of the magnetic field, temperature, the conductivities of two phases without magnetic field, and the thickness and conductivity of the interracial shells. The MR increases with the increase of the magnetic field and with the decrease of temperature, and no saturation is found even under the high magnetic field. Moreover, it is interestingly found that the interracial shell is an important factor for the MR of the composites. The MR increases with the thickness and the conductivity of the interfacial shells. Lastly, the theoretical results on the MR are compared with the experimental data. It is found that the value of the MR of the composite with the interfacial shell is larger than that without the interfacial shell.
文摘A complete model of Metal-Semiconductor-Metal Photodetector(MSM-PD) is presented. It can be used in any circuit simulators. Simulated DC characteristics for a GaAs MSM-PD are in good agreement with reported results.
文摘Variable-energy positron annihilation spectroscopy has been applied to study interfaces in Al/Si, Au/Si and Au/GaAs structures. Computational fittings of ROYPROF program were used to analyze Doppler broadening results in order to determine kinds of regions that positrons were likely to sample. The interfaces were found acting as a capturing thin layer with negligible positrons stopped in them and their characteristics came only from positrons diffusing to these interfaces, the positron work function of these materials were taken into consideration. In all fittings, the interfaces are found to have 1 nm thickness and act as an absorbing sink for all thermal positrons diffusing towards them, and this indicates either the existence of open volume defects or a weakness of known theoretical models for positron affinities. The result is supported by measurements obtained by applying external electric fields on Al/Si sample. Theoretical fittings have clearly demonstrated the sensitivity of interfaces in these attempts and their importance in data analyzing and in developing of fitting cods.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 41172110 and 61107090） and Shandong Provincial Natural Science Foundation （Grant No. ZR2011BZ007）.
基金supported by the Australian Research Council(ARC)Future Fellowship Scheme(FT210100509)ARC Discovery Project(DP220101959)+2 种基金the Hebrew University of Jerusalem--Zelman Cowen Academic Initiatives(zCAl)Joint Projects 2021,the Innovation and Technology Commission(grant no.MHP/104/21)Shenzhen Science Technology and Innovation Commission(grant no.20210324125612035)City University of Hong Kong(grant no.9360140).
文摘Emerging engineering strategies of colloidal metal-semiconductor nanorod hybrid nanostructures spanning from type,size,dimension,and location of both metal nanoparticles and semiconductors,co-catalyst,band gap structure,surface ligand to hole scavenger are elaborated symmetrically to rationalize the design of this type of intriguing materials for efficient photocatalytic applications.
