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71.
We observed the two-dimensional plasmons of the two-component electron plasma in the (001) Si-inversion layer resulting from simultaneous population of the [001] valley, E0, and the [010] valley, E0′, subbands under a compressional uniaxial stress along [010]. Our data show an onset of electron transfer from E0 to E0′ at X = (1.4 ± 0.1) kbar for n = 1.67 × 1012 cm?2 and X = (1.2 ± 0.2) kbar for n = 2.60 × 1012 cm?2, consistent with the theory of Takada and Ando that includes the electron-electron correlation effects. 相似文献
72.
D.C. Tsui 《Solid State Communications》1977,21(7):675-678
The transverse magnetoconductivity (σχχ) of electron inversion layers on (100) Si is measured in magnetic fields up to 220 kG at temperatures from 4.2 to 1.6 K. The dependence of σχχ on T, H, and the electric field along the inversion layer suggests that immobile electrons between two Landau subbands are to a large extent localized out of the top of the lower subband. Fine structure, which may be indicative of inhomogeneities of electronic origin, is observed in σχχ vs electron density. 相似文献
73.
We show that the application of a compressional stress to the Si substrate decreases the mobility of electrons in the lowest subband and causes piezoresistance. This effect, together with the electron transfer effect and the existence of localized band-tail states in the subbands at low electron densities, account for the piezoresistance in n-channel (100)Si inversion layer at 4.2 K. 相似文献
74.
We determine the fundamental group of a closed n-manifold of positive sectional curvature on which a torus Tk (k large) acts effectively and isometrically. Our results are: (A) If k>(n − 3)/4 and n ≥ 17, then the fundamental group π1(M) is isomorphic to the fundamental group of a spherical 3-space form. (B) If k ≥ (n/6)+1 and n≠ 11, 15, 23, then any abelian subgroup of π1(M) is cyclic. Moreover, if the Tk-fixed point set is empty, then π1(M) is isomorphic to the fundamental group of a spherical 3-space form.Mathematics Subject Classification (2000). 53-XX*Supported partially by NSF Grant DMS 0203164 and by a reach found from Beijing normal university.**Supported partially by NSFC 10371008. 相似文献
75.
We observed narrow-band far infrared emission from Si-MOSFETs with metallic gratings fabricated on the optically semitransparent gate. The gate voltage dependence of the emission frequency, analyzed by a magnetic field tuned detector, shows that it results from radiative decay of the two-dimensional metallic grating. 相似文献
76.
An additional splitting of Shubnikov-de Haas oscillations in (lll) n-type silicon inversion layers in observed. We attribute it to valley splitting, analogous to that previously observed on (100) surface layers, and point out that theoretical explanations of valley splitting, restricted to the valley configuration in (100) inversion layers, are not applicable. 相似文献
77.
通过控制共沉淀时溶液中Cd/Sn摩尔比的方法,合成了物相组成不同的CdO-SnO2复合氧化物粉料,探讨了相组成与材料电导及气敏性能之间的关系。 相似文献
78.
Z. Yang D. Peng A. Clough C.-H. Lam O.K.C. Tsui 《The European physical journal. Special topics》2010,189(1):155-164
Experiments in the past 1.5 decades have found that the glass transition temperature of polymer films can be noticeably different
from the bulk when the film thickness is decreased below ∼100 nm. On the other hand, many dynamic measurements have found
results inconsistent with the observed change in the glass transition temperature. One frequently cited reason is that the
dynamic properties being probed may not be directly related to the glass transition. Viscosity is a property traditionally
used to characterize the dynamic slowing down occurring to a material at the glass transition. In this paper, we report experimental
result showing that the viscosity of polystyrene films supported by oxide-coated silicon decreases with decreasing film thickness,
consistent with the observed glass transition temperature of the films. 相似文献
79.
W. Pan J.S. Xia D.C. Tsui E.D. Adams L.N. Pfeiffer K.W. West 《Solid State Communications》2006,140(2):88-93
In this paper, we review low temperature electronic transport results in high quality two-dimensional electron systems. We discuss the quantization of the diagonal resistance, Rxx, at the edges of several quantum Hall states. Each quantized Rxx value turns out to be close to the difference between the two adjacent Hall plateaus in the off-diagonal resistance, Rxy. Moreover, peaks in Rxx occur at different positions in positive and negative magnetic fields. All three Rxx features can be explained quantitatively by a ∼1% cm electron density gradient. Furthermore, based on this observation, the well known but still enigmatic resistivity rule, relating Rxx to , finds a simple interpretation in terms of this gradient. In another sample, at 1.2 K, Rxx we observe a strongly linear magnetic field dependence. Surprisingly, this linear magnetoresistance also originates from the density gradient. Our findings throw an unexpected light on the relationship between the experimentally measured Rxx and the diagonal resistivity ρxx. 相似文献
80.
Yongbo Bian Jin Guo Changzheng Gao Chunguang Li Hong Li Jia Wang Bin Cui Xiaofeng He Chao Li Na Li Guoqiang Li Qiang Zhang Xueqiang Zhang Jibao Meng Yusheng He 《Physica C: Superconductivity and its Applications》2010,470(15-16):617-621
This paper presents a miniaturized high performance high temperature superconducting (HTS) microwave receiver front-end subsystem, which uses a mini stirling cryocooler to cool a high selective HTS filter and a low noise amplifier (LNA). The HTS filter was miniaturized by using specially designed compact resonators and fabricating with double-sided YBCO films on LAO substrate which has a relatively high permittivity. The LNA was specially designed to work at cryogenic temperature with noise figure of 0.27 dB at 71 K. The mini cryocooler, which is widely used in infrared detectors, has a smaller size (60 mm × 80 mm × 100 mm) and a lighter weight (340 g) than the stirling cryocoolers commonly used in other HTS filter subsystem. The whole front-end subsystem, including a HTS filter, a LNA, a cryocooler and the vacuum chamber, has a size of only φ120 mm × 175 mm and a weight of only 3.3 kg. The microwave devices inside the subsystem are working at 71.8 K with a consumed cooling power of 0.325 W. The center frequency of this subsystem is 925.2 MHz and the bandwidth is 2.7 MHz (which is a fractional bandwidth of 0.2%), with the gain of 19.75 dB at center frequency and the return loss better than ?18.11 dB in the pass band. The stop band rejection is more than 60 dB and the skirt slope is exceeding 120 dB MHz?1. The noise figure of this subsystem is less than 0.8 dB. This front-end subsystem can be used in radars and communication systems conveniently due to it’s compact size and light weight. 相似文献