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[en] There is a great difference in behavior of e- in liquid hydrogen and helium despite the fact that the adopted theories of the mobility are quite similar. Recently, Levchenko and Mezhov-Deglin reported large discrepancies of the mobility of the electrons in liquid hydrogen from estimates based on the theory that the electrons are trapped in bubbles forming atomlike structures (open-quotes bubbloniumclose quotes). They properly suggested that these deviations are related to the existence in liquid hydrogen of another, metastable type of negative charge carrier. The subject of the current paper is the physical explanation of the existence of two types of carriers in liquid hydrogen. The authors attribute the second type of carriers to the cluster ion H-(H2)x, which is created by the formation of solid hydrogen around a bound state of degradation of the open-quotes snowballclose quotes formed around the H- ion on the basis of energy diagrams for a hydride ion submerged in liquid hydrogen
[en] As a promising substitute for periodical metamaterials, random composites with tunable negative electromagnetic parameters, which are termed as metacomposites, have drawn extensive attention owing to their unique properties and great potential applications. It is significant to decrease the values of negative permittivity and attain weakly negative permittivity with low frequency dispersive behavior, when searching for substitutable metacomposites. In this paper, the absolute value of negative permittivity in graphene/epoxy resin composites was dramatically decreased to approximately 6 by controlling the content of graphene and the microstructure of the resultant composites. Meanwhile, the permittivity spectrum showed low frequency dispersive behavior, which kept steady in a wide scope of frequency. It is indicated that the independence of negative permittivity on frequency results from the outstanding electron mobility of graphene. Moreover, it is demonstrated that the positive permittivity is ascribed to capacitive character, and the inductive character results in negative permittivity.
[en] A maximum in the electron mobility versus density is reported for the polyatomic molecular liquid, 2,2-dimethylbutane. Also, enhanced electron scattering is observed in the gas phase at densities just below the critical density
[en] An analytical model for the mobility of electrons in surface charge coupled devices is studied on the basis of the results previously obtained, considering a surface diffuse scattering; the importance of the results obtained for a better understanding of the influence of the fringing field in surface charge coupled devices is discussed. (author)
[en] In this paper, we report the recent progress in the high-frequency performance of enhancement-mode devices in the novel N-polar GaN technology and provide a pathway for further scaling. The intrinsic advantages of electron confinement, polarization doping of the back-barrier and the absence of a source barrier in N-polar GaN technology were leveraged with polarization engineering with a top barrier for enhancement mode operation and advanced self-aligned source/drain technology for low parasitic access resistances. The scalability of the device structures are explored in terms of short-channel effects and high-frequency performance. Low-field electron mobility in vertically scaled channel was also investigated providing insights on the scattering mechanism. (invited review)
[en] A broadband miniature doubly balanced diode mixer chip fabricated by Win's 0.15 μm pHEMT technology is presented. In order to save chip area, a four-fold modified Marchand balun is used. A coupled line U section improves the port to port isolation and provides the IF-output port. The mixer achieves a low conversion loss of 5.5 to 10.7 dB and high isolation of more than 26 dB over a 26-40 GHz RF/LO bandwidth and a DC-14 GHz IF bandwidth. The mixer's chip size is around 0.96 mm2. (semiconductor integrated circuits)
[en] The extraordinary properties and the novel applications of black phosphorene induce the research interest in the monolayer group-IV monochalcogenides. Here using first-principles calculations, we systematically investigate the electronic, transport, and optical properties of monolayer α- and β-GeSe, revealing a direct band gap of 1.61 eV for monolayer α-GeSe and an indirect band gap of 2.47 eV for monolayer β-GeSe. For monolayer β-GeSe, the electronic/hole transport is anisotropic, with an extremely high electron mobility of 2.93×104cm2/Vs along the armchair direction, comparable to that of black phosphorene. However, for β-GeSe, robust band gaps nearly independent of the applied tensile strain along the armchair direction are observed. Both monolayer α- and β-GeSe exhibit anisotropic optical absorption in the visible spectrum.
[en] This paper describes an analytical model for bulk electron mobility in strained-Si layers as a function of strain. Phonon scattering, columbic scattering and surface roughness scattering are included to analyze the full mobility model. Analytical explicit calculations of all of the parameters to accurately estimate the electron mobility have been made. The results predict an increase in the electron mobility with the application of biaxial strain as also predicted from the basic theory of strain physics of metal oxide semiconductor (MOS) devices. The results have also been compared with numerically reported results and show good agreement. (semiconductor devices)