In this paper, in order to solve the interface-trap issue and enhance the transconductance induced by high-k dielectric in metal-insulator-semiconductor （MIS） high electron mobility transistors （HEMTs）, we demonst...In this paper, in order to solve the interface-trap issue and enhance the transconductance induced by high-k dielectric in metal-insulator-semiconductor （MIS） high electron mobility transistors （HEMTs）, we demonstrate better performances of recessed-gate A1203 MIS-HEMTs which are fabricated by Fluorine-based Si3N4 etching and chlorine- based A1CaN etching with three etching times （15 s, 17 s and 19 s）. The gate leakage current of MIS-HEMT is about three orders of magnitude lower than that of A1GaN/CaN HEMT. Through the recessed-gate etching, the transconductanee increases effectively. When the recessed-gate depth is 1.02 nm, the best interface performance with Tit----（0.20--1.59） p^s and Dit ：（0.55-1.08）x 1012 cm-2.eV- 1 can be obtained. After chlorine-based etching, the interface trap density reduces considerably without generating any new type of trap. The accumulated chlorine ions and the N vacancies in the AIGaN surface caused by the plasma etching can degrade the breakdown and the high frequency performances of devices. By comparing the characteristics of recessed-gate MIS-HEMTs with different etching times, it is found that a low power chlorine-based plasma etching for a short time （15 s in this paper） can enhance the performances of MIS-HEMTs effectively.展开更多
The Three Gorges Project has always been under global spotlight, even when it was still being conceived in the 1980s. No wonder. The project, scheduled for completion by 2010, will be the greatest hydroelectric projec...The Three Gorges Project has always been under global spotlight, even when it was still being conceived in the 1980s. No wonder. The project, scheduled for completion by 2010, will be the greatest hydroelectric project ever built by the human race. Moreover, some 1.2 million people are being resettled in the course of its construction, the largest human exodus caused by any construction project ever undertaken in the world.展开更多
Achieving high thermal conductivity in polymer composites with micro or nanoparticle fillers are challenging.Typically,over 50 vol%filler loading is necessary to form a thermal conductive network.However,even with suc...Achieving high thermal conductivity in polymer composites with micro or nanoparticle fillers are challenging.Typically,over 50 vol%filler loading is necessary to form a thermal conductive network.However,even with such a network in place,the increase in thermal conductivity may not be significant compared to that in electrically conductive composites.To clarify the ideal filler network structure,we endeavored to selectively disperse nano-sized Al_(2)O_(3)nanoparticles at the interface of co-continuous SEBS/PA6 blends,with and without various filler surface modification methods.A thermal conductive network forms when all interface areas are fully covered by 2.56 vol%of Al_(2)O_(3)nanoparticles(very close to theoretical loading content 2.29 vol%).In this case,the Al_(2)O_(3)nanoparticle has the highest thermal conductive contribution(TCC).However,the absolute TCC values are extremely low because of the interfacial thermal resistance and it will decrease when the filler content exceeds 2.56 vol%,indicating that some nanoparticles are dispersed separately out of the existed thermal conductive network.These findings suggest that the construction of a connected thermal conductive network,relatively lower interfacial thermal resistance and the precise positioning of fillers within this network are essential for achieving high thermal conductivity composites.展开更多
基金supported by the National Key Science and Technology Special Project,China (Grant No. 2008ZX01002-002)the National Natural Science Foundation of China (Grant No. 60736033)
文摘In this paper, in order to solve the interface-trap issue and enhance the transconductance induced by high-k dielectric in metal-insulator-semiconductor （MIS） high electron mobility transistors （HEMTs）, we demonstrate better performances of recessed-gate A1203 MIS-HEMTs which are fabricated by Fluorine-based Si3N4 etching and chlorine- based A1CaN etching with three etching times （15 s, 17 s and 19 s）. The gate leakage current of MIS-HEMT is about three orders of magnitude lower than that of A1GaN/CaN HEMT. Through the recessed-gate etching, the transconductanee increases effectively. When the recessed-gate depth is 1.02 nm, the best interface performance with Tit----（0.20--1.59） p^s and Dit ：（0.55-1.08）x 1012 cm-2.eV- 1 can be obtained. After chlorine-based etching, the interface trap density reduces considerably without generating any new type of trap. The accumulated chlorine ions and the N vacancies in the AIGaN surface caused by the plasma etching can degrade the breakdown and the high frequency performances of devices. By comparing the characteristics of recessed-gate MIS-HEMTs with different etching times, it is found that a low power chlorine-based plasma etching for a short time （15 s in this paper） can enhance the performances of MIS-HEMTs effectively.
文摘The Three Gorges Project has always been under global spotlight, even when it was still being conceived in the 1980s. No wonder. The project, scheduled for completion by 2010, will be the greatest hydroelectric project ever built by the human race. Moreover, some 1.2 million people are being resettled in the course of its construction, the largest human exodus caused by any construction project ever undertaken in the world.
基金supported by the National Natural Science Foundation of China(Nos.51973052 and 51473047)。
文摘Achieving high thermal conductivity in polymer composites with micro or nanoparticle fillers are challenging.Typically,over 50 vol%filler loading is necessary to form a thermal conductive network.However,even with such a network in place,the increase in thermal conductivity may not be significant compared to that in electrically conductive composites.To clarify the ideal filler network structure,we endeavored to selectively disperse nano-sized Al_(2)O_(3)nanoparticles at the interface of co-continuous SEBS/PA6 blends,with and without various filler surface modification methods.A thermal conductive network forms when all interface areas are fully covered by 2.56 vol%of Al_(2)O_(3)nanoparticles(very close to theoretical loading content 2.29 vol%).In this case,the Al_(2)O_(3)nanoparticle has the highest thermal conductive contribution(TCC).However,the absolute TCC values are extremely low because of the interfacial thermal resistance and it will decrease when the filler content exceeds 2.56 vol%,indicating that some nanoparticles are dispersed separately out of the existed thermal conductive network.These findings suggest that the construction of a connected thermal conductive network,relatively lower interfacial thermal resistance and the precise positioning of fillers within this network are essential for achieving high thermal conductivity composites.
