The effects of various factors on the electrocarboxylation of organic compounds with carbon dioxide catalyzed by metalloporphyrin are studied.The optimal potential of electrocar- boxylation is -1.6 V(vs.SCE).A weak pr...The effects of various factors on the electrocarboxylation of organic compounds with carbon dioxide catalyzed by metalloporphyrin are studied.The optimal potential of electrocar- boxylation is -1.6 V(vs.SCE).A weak protic solvent methanol can enhance catalytic activity. Tetrabutylammonium iodide is the best one of five electrolytes.The yields and current efficiencies of electrocarboxylation are increased slowly as the concentration of catalyst increases.展开更多
随着栅极长度、硅膜厚度以及埋氧层厚度的减小,MOS器件短沟道效应变得越来越严峻。本文首先给出了决定全耗尽绝缘体上硅短沟道效应的三种机制;然后从接地层、埋层工程、沟道工程、源漏工程、侧墙工程和栅工程等六种工程技术方面讨论了...随着栅极长度、硅膜厚度以及埋氧层厚度的减小,MOS器件短沟道效应变得越来越严峻。本文首先给出了决定全耗尽绝缘体上硅短沟道效应的三种机制;然后从接地层、埋层工程、沟道工程、源漏工程、侧墙工程和栅工程等六种工程技术方面讨论了为抑制短沟道效应而引入的不同UTBB SOI MOSFETs结构,分析了这些结构能够有效抑制短沟道效应(如漏致势垒降低、亚阈值摆幅、关态泄露电流、开态电流等)的机理;而后基于这六种技术,对近年来在UTBB SOI MOSFETs短沟道效应抑制方面所做的工作进行了总结;最后对未来技术的发展进行了展望。展开更多
This manuscript explores the behavior of a junctionless tri-gate FinFET at the nano-scale region using SiGe material for the channel.For the analysis,three different channel structures are used:(a)tri-layer stack chan...This manuscript explores the behavior of a junctionless tri-gate FinFET at the nano-scale region using SiGe material for the channel.For the analysis,three different channel structures are used:(a)tri-layer stack channel(TLSC)(Si-SiGe-Si),(b)double layer stack channel(DLSC)(SiGe-Si),(c)single layer channel(SLC)(S_(i)).The I−V characteristics,subthreshold swing(SS),drain-induced barrier lowering(DIBL),threshold voltage(V_(t)),drain current(ION),OFF current(IOFF),and ON-OFF current ratio(ION/IOFF)are observed for the structures at a 20 nm gate length.It is seen that TLSC provides 21.3%and 14.3%more ON current than DLSC and SLC,respectively.The paper also explores the analog and RF factors such as input transconductance(g_(m)),output transconductance(gds),gain(gm/gds),transconductance generation factor(TGF),cut-off frequency(f_(T)),maximum oscillation frequency(f_(max)),gain frequency product(GFP)and linearity performance parameters such as second and third-order harmonics(g_(m2),g_(m3)),voltage intercept points(VIP_(2),VIP_(3))and 1-dB compression points for the three structures.The results show that the TLSC has a high analog performance due to more gm and provides 16.3%,48.4%more gain than SLC and DLSC,respectively and it also provides better linearity.All the results are obtained using the VisualTCAD tool.展开更多
Using the semi-insulating property and small lattice constant a of wurtzite BGaN alloy, we propose a BGaN buffer with a B-content of 1% to enhance two-dimensional electron gas(2 DEG) confinement in a short-gate AlGaN/...Using the semi-insulating property and small lattice constant a of wurtzite BGaN alloy, we propose a BGaN buffer with a B-content of 1% to enhance two-dimensional electron gas(2 DEG) confinement in a short-gate AlGaN/GaN highelectron mobility transistor(HEMT). Based on the two-dimensional TCAD simulation, the direct current(DC) and radio frequency(RF) characteristics of the AlGaN/GaN/B_(0.01)Ga_(0.99)N structure HEMTs are theoretically studied. Our results show that the BGaN buffer device achieves good pinch-off quality and improves RF performance compared with GaN buffer device. The BGaN buffer device can allow a good immunity to shift of threshold voltage for the aspect ratio(LG/d)down to 6, which is much lower than that the GaN buffer device with L_G/d=11 can reach. Furthermore, due to a similar manner of enhancing 2 DEG confinement, the B_(0.01)Ga_(0.99)N buffer device has similar DC and RF characteristics to those the AlGaN buffer device possesses, and its ability to control short-channel effects(SCEs) is comparable to that of an Al_(0.03)Ga_(0.97)N buffer. Therefore, this BGaN buffer with very small B-content promises to be a new method to suppress SCEs in GaN HEMTs.展开更多
In this work, we use a 3-nm-thick Al0.64In0.36N back-barrier layer in In0.17Al0.83N/GaN high-electron mobility transistor （HEMT） to enhance electron confinement. Based on two-dimensional device simulations, the infl...In this work, we use a 3-nm-thick Al0.64In0.36N back-barrier layer in In0.17Al0.83N/GaN high-electron mobility transistor （HEMT） to enhance electron confinement. Based on two-dimensional device simulations, the influences of Al0.64In0.36N back-barrier on the direct-current （DC） and radio-frequency （RF） characteristics of InAlN/GaN HEMT are investigated, theoretically. It is shown that an effective conduction band discontinuity of approximately 0.5 eV is created by the 3-nm-thick Al0.64In0.36N back-barrier and no parasitic electron channel is formed. Comparing with the conventional InAlN/GaN HEMT, the electron confinement of the back-barrier HEMT is significantly improved, which allows a good immunity to short-channel effect （SCE） for gate length decreasing down to 60 nm （9-nm top barrier）. For a 70-nm gate length, the peak current gain cut-off frequency （fT） and power gain cut-off frequency （fmax） of the back-barrier HEMT are 172 GHz and 217 GHz, respectively, which are higher than those of the conventional HEMT with the same gate length.展开更多
N and P-channel groove-gate MOSFETs based on a self-aligned CMOS process have been fabricated and characterized. For the devices with channel length of 140nm, the measured drain induced barrier lowering （DIBL） was 6...N and P-channel groove-gate MOSFETs based on a self-aligned CMOS process have been fabricated and characterized. For the devices with channel length of 140nm, the measured drain induced barrier lowering （DIBL） was 66mV/V for n-MOSFETs and 82mV/V for p-MOSFETs. The substrate current of a groove-gate n-MOSFET was 150 times less than that of a conventional planar n-MOSFET, These results demonstrate that groove-gate MOSFETs have excellent capabilities in suppressing short-channel effects. It is worth emphasizing that our groove-gate MOSFET devices are fabricated by using a simple process flow, with the potential of fabricating devices in the sub-100nm range.展开更多
文摘The effects of various factors on the electrocarboxylation of organic compounds with carbon dioxide catalyzed by metalloporphyrin are studied.The optimal potential of electrocar- boxylation is -1.6 V(vs.SCE).A weak protic solvent methanol can enhance catalytic activity. Tetrabutylammonium iodide is the best one of five electrolytes.The yields and current efficiencies of electrocarboxylation are increased slowly as the concentration of catalyst increases.
文摘随着栅极长度、硅膜厚度以及埋氧层厚度的减小,MOS器件短沟道效应变得越来越严峻。本文首先给出了决定全耗尽绝缘体上硅短沟道效应的三种机制;然后从接地层、埋层工程、沟道工程、源漏工程、侧墙工程和栅工程等六种工程技术方面讨论了为抑制短沟道效应而引入的不同UTBB SOI MOSFETs结构,分析了这些结构能够有效抑制短沟道效应(如漏致势垒降低、亚阈值摆幅、关态泄露电流、开态电流等)的机理;而后基于这六种技术,对近年来在UTBB SOI MOSFETs短沟道效应抑制方面所做的工作进行了总结;最后对未来技术的发展进行了展望。
文摘This manuscript explores the behavior of a junctionless tri-gate FinFET at the nano-scale region using SiGe material for the channel.For the analysis,three different channel structures are used:(a)tri-layer stack channel(TLSC)(Si-SiGe-Si),(b)double layer stack channel(DLSC)(SiGe-Si),(c)single layer channel(SLC)(S_(i)).The I−V characteristics,subthreshold swing(SS),drain-induced barrier lowering(DIBL),threshold voltage(V_(t)),drain current(ION),OFF current(IOFF),and ON-OFF current ratio(ION/IOFF)are observed for the structures at a 20 nm gate length.It is seen that TLSC provides 21.3%and 14.3%more ON current than DLSC and SLC,respectively.The paper also explores the analog and RF factors such as input transconductance(g_(m)),output transconductance(gds),gain(gm/gds),transconductance generation factor(TGF),cut-off frequency(f_(T)),maximum oscillation frequency(f_(max)),gain frequency product(GFP)and linearity performance parameters such as second and third-order harmonics(g_(m2),g_(m3)),voltage intercept points(VIP_(2),VIP_(3))and 1-dB compression points for the three structures.The results show that the TLSC has a high analog performance due to more gm and provides 16.3%,48.4%more gain than SLC and DLSC,respectively and it also provides better linearity.All the results are obtained using the VisualTCAD tool.
基金Project supported by the Foundation Project of the Science and Technology on Electro-Optical Information Security Control Laboratory,China(Grant No.614210701041705)
文摘Using the semi-insulating property and small lattice constant a of wurtzite BGaN alloy, we propose a BGaN buffer with a B-content of 1% to enhance two-dimensional electron gas(2 DEG) confinement in a short-gate AlGaN/GaN highelectron mobility transistor(HEMT). Based on the two-dimensional TCAD simulation, the direct current(DC) and radio frequency(RF) characteristics of the AlGaN/GaN/B_(0.01)Ga_(0.99)N structure HEMTs are theoretically studied. Our results show that the BGaN buffer device achieves good pinch-off quality and improves RF performance compared with GaN buffer device. The BGaN buffer device can allow a good immunity to shift of threshold voltage for the aspect ratio(LG/d)down to 6, which is much lower than that the GaN buffer device with L_G/d=11 can reach. Furthermore, due to a similar manner of enhancing 2 DEG confinement, the B_(0.01)Ga_(0.99)N buffer device has similar DC and RF characteristics to those the AlGaN buffer device possesses, and its ability to control short-channel effects(SCEs) is comparable to that of an Al_(0.03)Ga_(0.97)N buffer. Therefore, this BGaN buffer with very small B-content promises to be a new method to suppress SCEs in GaN HEMTs.
基金supported by the Natural Science Foundation of Hebei Province,China(Grant No.F2013202256)
文摘In this work, we use a 3-nm-thick Al0.64In0.36N back-barrier layer in In0.17Al0.83N/GaN high-electron mobility transistor （HEMT） to enhance electron confinement. Based on two-dimensional device simulations, the influences of Al0.64In0.36N back-barrier on the direct-current （DC） and radio-frequency （RF） characteristics of InAlN/GaN HEMT are investigated, theoretically. It is shown that an effective conduction band discontinuity of approximately 0.5 eV is created by the 3-nm-thick Al0.64In0.36N back-barrier and no parasitic electron channel is formed. Comparing with the conventional InAlN/GaN HEMT, the electron confinement of the back-barrier HEMT is significantly improved, which allows a good immunity to short-channel effect （SCE） for gate length decreasing down to 60 nm （9-nm top barrier）. For a 70-nm gate length, the peak current gain cut-off frequency （fT） and power gain cut-off frequency （fmax） of the back-barrier HEMT are 172 GHz and 217 GHz, respectively, which are higher than those of the conventional HEMT with the same gate length.
基金Project supported by the National Natural Science Foundation of China （Grant No 60376024）.
文摘N and P-channel groove-gate MOSFETs based on a self-aligned CMOS process have been fabricated and characterized. For the devices with channel length of 140nm, the measured drain induced barrier lowering （DIBL） was 66mV/V for n-MOSFETs and 82mV/V for p-MOSFETs. The substrate current of a groove-gate n-MOSFET was 150 times less than that of a conventional planar n-MOSFET, These results demonstrate that groove-gate MOSFETs have excellent capabilities in suppressing short-channel effects. It is worth emphasizing that our groove-gate MOSFET devices are fabricated by using a simple process flow, with the potential of fabricating devices in the sub-100nm range.
