High frequency properties of 4H-SiC double drift region (DDR) Mixed Tunnelling Avalanche Transit Time (MITATT) diodes are studied through computer simulation method. It is interesting to observe that the efficiency of...High frequency properties of 4H-SiC double drift region (DDR) Mixed Tunnelling Avalanche Transit Time (MITATT) diodes are studied through computer simulation method. It is interesting to observe that the efficiency of SiC (flat) DDR MITATT diode (16%) is more than 4 times that of Si (flat) DDR MITATT diode (3.59%). In addition, a power output of more than 15 times from the SiC MITATT diode compared to the Si MITATT diode is commendable. A reduced noise measure of 17.71 dB from a low-high-low (lo-hi-lo) structure compared to that of 21.5 dB from a flat structure of SiC is indicative of the favourable effect of tunnelling current on the MITATT diode performance.展开更多
The search for quantum spin liquid(QSL) materials has attracted significant attention in the field of condensed matter physics in recent years, however so far only a handful of them are considered as candidates hostin...The search for quantum spin liquid(QSL) materials has attracted significant attention in the field of condensed matter physics in recent years, however so far only a handful of them are considered as candidates hosting QSL ground state. Owning to their geometrically frustrated structures, Kagome materials are ideal systems to realize QSL. We synthesize the kagome structured material claringbullite(Cu_4(OH)_6FCl) and then replace inter-layer Cu with Zn to form Cu_3Zn(OH)_6FCl. Comprehensive measurements reveal that doping Zn^(2+) ions transforms magnetically ordered Cu_4(OH)_6FCl into a non-magnetic QSL candidate Cu_3Zn(OH)_6FCl. Therefore,the successful syntheses of Cu_4(OH)_6FCl and Cu_3Zn(OH)_6FCl provide not only a new platform for the study of QSL but also a novel pathway of investigating the transition between QSL and magnetically ordered systems.展开更多
The potential of GaN as a wide band gap semiconductor is explored for application as double drift region mixed tunneling avalanche transit time （MITATT） diodes for operation at 120 GHz, 220 GHz and 0.35 THz using so...The potential of GaN as a wide band gap semiconductor is explored for application as double drift region mixed tunneling avalanche transit time （MITATT） diodes for operation at 120 GHz, 220 GHz and 0.35 THz using some computer simulation methods developed by our group. The salient features of our results have uncovered some peculiarities of the GaN based MITATT devices. An efficiency of more than 20% right up to a frequency of 0.35 THz （from the GaN MITATT diode） seems highly encouraging but a power output of only 0.76 W is indicative of its dismal fate. The existence of a noise measure minimum at the operating frequency of 0.35 THz is again exhilarating but the value of the minimum is miserably high i.e. more than 33 dB. Thus, although GaN is a wide band gap semiconductor, the disparate carrier velocities prevent its full potential from being exploited for application as MTATT diodes.展开更多
文摘High frequency properties of 4H-SiC double drift region (DDR) Mixed Tunnelling Avalanche Transit Time (MITATT) diodes are studied through computer simulation method. It is interesting to observe that the efficiency of SiC (flat) DDR MITATT diode (16%) is more than 4 times that of Si (flat) DDR MITATT diode (3.59%). In addition, a power output of more than 15 times from the SiC MITATT diode compared to the Si MITATT diode is commendable. A reduced noise measure of 17.71 dB from a low-high-low (lo-hi-lo) structure compared to that of 21.5 dB from a flat structure of SiC is indicative of the favourable effect of tunnelling current on the MITATT diode performance.
基金Supported by the National Key Research and Development Program(2016YFA0300502,2017YFA0302901,2016YFA0300604 and 2016YFA0300501)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB28000000,XDB07020100and QYZDB-SSW-SLH043)the National Natural Science Foundation of China under Grant Nos 11421092,11574359,11674370,11774399,11474330 and U1732154
文摘The search for quantum spin liquid(QSL) materials has attracted significant attention in the field of condensed matter physics in recent years, however so far only a handful of them are considered as candidates hosting QSL ground state. Owning to their geometrically frustrated structures, Kagome materials are ideal systems to realize QSL. We synthesize the kagome structured material claringbullite(Cu_4(OH)_6FCl) and then replace inter-layer Cu with Zn to form Cu_3Zn(OH)_6FCl. Comprehensive measurements reveal that doping Zn^(2+) ions transforms magnetically ordered Cu_4(OH)_6FCl into a non-magnetic QSL candidate Cu_3Zn(OH)_6FCl. Therefore,the successful syntheses of Cu_4(OH)_6FCl and Cu_3Zn(OH)_6FCl provide not only a new platform for the study of QSL but also a novel pathway of investigating the transition between QSL and magnetically ordered systems.
文摘The potential of GaN as a wide band gap semiconductor is explored for application as double drift region mixed tunneling avalanche transit time （MITATT） diodes for operation at 120 GHz, 220 GHz and 0.35 THz using some computer simulation methods developed by our group. The salient features of our results have uncovered some peculiarities of the GaN based MITATT devices. An efficiency of more than 20% right up to a frequency of 0.35 THz （from the GaN MITATT diode） seems highly encouraging but a power output of only 0.76 W is indicative of its dismal fate. The existence of a noise measure minimum at the operating frequency of 0.35 THz is again exhilarating but the value of the minimum is miserably high i.e. more than 33 dB. Thus, although GaN is a wide band gap semiconductor, the disparate carrier velocities prevent its full potential from being exploited for application as MTATT diodes.
