共查询到20条相似文献,搜索用时 15 毫秒
1.
Zirconium oxide layers have been successfully deposited by photo-CVD at low temperatures. ZrO2 growth was observed at temperatures as low as 100 °C. When deposited at 250 °C and above, these films exhibited a polycrystalline
structure with a mixture of different crystal phases. Deposition at 300 °C was found to form moisture-free ZrO2 films with a high refractive index of 2.1, a very low effective density of trapped electrons of ∼8.8×108 cm-2 and an interface trap density of 6.6×109 cm-2 eV-1 being readily obtained.
Received: 17 December 2001 / Accepted: 6 January 2002 / Published online: 3 June 2002 相似文献
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The electro-optical Kerr effect induced by a slowly varying electric field in liquid helium at temperatures below the lambda point is investigated. The Kerr constant of liquid helium is measured to be (1.43+/-0.02(stat)+/-0.04(sys)) x 10(-20) (cm/V)(2) at T=1.5 K. Within experimental uncertainty, the Kerr constant is independent of temperature in the range T=1.5 K to 2.17 K, which implies that the Kerr constant of the superfluid component of liquid helium is the same as that of normal liquid helium. Pair and higher correlations of He atoms in the liquid phase account for about 23% of the measured Kerr constant. Liquid nitrogen was used to test the experimental setup; the result for the liquid nitrogen Kerr constant is (4.38+/-0.15) x 10(-18) (cm/V)(2). Kerr effect can be used as a noncontact technique for measuring the magnitude and mapping out the distribution of electric fields inside these cryogenic insulants. 相似文献
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B. E. Kane N. S. McAlpine R. G. Clark 《Physica E: Low-dimensional Systems and Nanostructures》2000,8(4)
We propose here a technique for precision deposition of single atoms or ordered arrays of atoms onto a substrate by first suspending the atoms as ions within a superfluid 4He film adhering to the substrate via van der Waals forces. The ions are held within the film by a combination of image forces and an externally applied electric field. Turning off the electric field causes the ions to fall toward the substrate and bond to the substrate surface. If the applied electric field comes from a scanned probe above the film, individual atoms can be deposited with atomic precision. A uniform applied electric field can be used to deposit a crystal of ions onto the substrate. 相似文献
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The resistivity of Cu, Cu + 100 ppm Fe and Cu + 200 ppm Fe films was measured as a function of temperature from 1 to 300 K. The results on films evaporated at room temperature are compared with contradicting data of other authors. Disordered CuFe alloy films, produced by evaporation onto a substrate at helium temperature, failed to show the theoretically predicted temperature shift of the resistivity minimum. 相似文献
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We report the observation of giant photo induced optical bleaching in Sb/As2S3 multilayered film at room and liquid He temperatures, when irradiated with 532 nm laser at moderate intensities. The experimental results show a dramatic increase in transmittance near the band gap regime at both the temperatures; however the rates at which transmission change occurs are rather slow at low temperature. The huge change in transmission is due to the photo induced intermixing of As2S3 layer with Sb. Our XPS measurements show that photo induced intermixing occurs through the wrong homopolar bonds, which under actinic light illumination are converted into energetically favored hetropolar bonds. 相似文献
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The elastic constants of single crystal galena have been determined from the measured ultrasonic velocities down to liquid
helium temperature. A cryostat incorporating an arrangement to inject the liquid bonding material at low temperature is described.
At 5 K, the values of elastic constants are C11=14.90, C12=3.51 and C44=2.92×1010 N/m2. 相似文献
9.
Klaus Froböse 《Zeitschrift für Physik B Condensed Matter》1977,26(1):19-27
We derive an expression for the low-temperature electrical resistivity in simple monovalent metals caused by electron-impurity and electron-phonon scattering. Since the recent measurements of the electrical resistivity of van Kempen et al. give direct evidence for the existence of phonon drag we take phonon drag into account. Our expression is exact in the limit of strong electron-impurity scattering. For the model of an acoustically isotropic metal we obtain a simple analytical formula which reproduces the experimental data on potassium fairly well, with both fitparameters, the sound velocity and the pseudopotential, being close to the values expected from other data. 相似文献
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A set of experiments dedicated to investigations of local electronic transport in undoped InAs nanowires at liquid helium temperatures in the presence of a charged atomic-force microscope tip has been presented. Both nanowires without defects and with internal tunneling barriers were studied. The measurements were performed at various carrier concentrations in the systems and opacity of contact-to-wire interfaces. The regime of Coulomb blockade is investigated in detail including negative differential conductivity of the whole system. The situation with open contacts with one tunneling barrier and undivided wire is also addressed. Special attention is devoted to recently observed quasi-periodic standing waves. 相似文献
11.
Acoustic relaxation in undeformed and plastically deformed CsI single crystal has been studied using the composite oscillator
technique at frequencies (1–7) × 105 Hz in the temperature range 2–15 K. Plastic deformation leads to appearance of an internal friction peak localized in the
temperature interval 4–5 K. It is shown that the peak shifts towards higher temperatures when increasing the vibration frequency
and corresponds to a thermally activated relaxation process with very low values of the activation energyU ≈ 1.9×10−3 eV and the attack frequencyν
0≈6.7 × 103 s−1. Interaction of sound with dislocation kinks migrating in the second order Peierls relief is considered as a possible mechanism
of the peak.
Research was made possible in part by Grants U9T000 and U9T200 from the International Science Foundation and supported in
part by the Fundamental Research Foundation of Ukraine (Project 2.4/156 “Bion”). 相似文献
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V.A. Benderskii V.Kh. Brikenstein V.L. Broude A.G. Lavrushko 《Solid State Communications》1974,15(8):1235-1237
Measurement of temperature pulses with time resolution less than 5 nsec based, on the high-speed registration of the Debye-Waller factor in the fluourescence spectrum of an impurity layer deposited on a sample, has been achieved. In anthracene single crystals, the velocity of heat propagation was found to be equal to 0.7?1.0.105 cm/sec, approaching that sound; the mean free path of phonons was found to exceed 30 μm. 相似文献
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Thin films of eight metals with a thickness of 150 nm were deposited on mica substrates by thermal evaporation at various temperatures in a high vacuum. The surface morphology of the metal films was observed by atomic force microscopy (AFM) and the images were characterized quantitatively by a roughness analysis and a bearing analysis (surface height analysis). The films of Au, Ag, Cu, and Al with the high melting points were prepared at homologous temperatures T/Tm = 0.22-0.32, 0.40, and 0.56. The films of In, Sn, Bi, and Pb with the low melting points were prepared at T/Tm = 0.55-0.70, where T and Tm are the absolute temperatures of the mica substrate and the melting point of the metal, respectively. The surface morphology of these metal films was studied based on a structure zone model. The film surfaces of Au, Ag, and Cu prepared at the low temperatures (T/Tm = 0.22-0.24) consist of small round grains with diameters of 30-60 nm and heights of 2-7 nm. The surface heights of these metal films distribute randomly around the surface height at 0 nm and the morphology is caused by self-shadowing during the deposition. The grain size becomes large due to surface diffusion of adatoms and the film surfaces have individual characteristic morphology and roughnesses as T increases. The surface of the Al film becomes very smooth as T increases and the atomically smooth surface is obtained at T/Tm = 0.56-0.67 (250-350 °C). On the other hand, the atomically smooth surface of the Au film is obtained at T/Tm = 0.56 (473 ± 3 °C). The films of In, Sn, Bi, and Pb prepared at T/Tm = 0.55-0.70 also show the individual characteristic surface morphology. 相似文献
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N.M. Liao W. Li Y.D. Jiang Y.J. Kuang K.C. Qi Z.M. Wu S.B. Li 《Applied Physics A: Materials Science & Processing》2008,91(2):349-352
The ordering evolution of the amorphous network of a-Si:H thin films with increasing initial silane-gas temperatures was investigated
by Raman spectroscopy. The results show that there exists a gradual ordering of the amorphous network, both in the near surface
and interior region on increasing the silane-gas temperature. In addition, the increase in the gas temperature leads to an
improved ordering of amorphous network on the short and intermediate scales towards the surface of a-Si:H thin films. Post-annealing
at 250 °C for 3 h mainly leads to a short and intermediate range improvement in the interior region of the films. Our present
results suggest that a-Si:H thin films with better quality could be deposited at higher silane-gas temperature.
PACS 63.50.+x; 61.43.-j; 75.40.-s 相似文献
17.
L. A. Maksimov V. L. Tsymbalenko 《Journal of Experimental and Theoretical Physics》1998,87(4):714-722
The growth rate of 4He crystals from superfluid is measured in the temperature range 1.2–1.75 K at supersaturations up to 40 mbar. The growth
rate is observed to decrease at high supersaturations: above 5 mbar in the bcc phase and above 20 mbar in the hcp phase. The
temperature dependence of the kinetic growth factor K is measured in the low-supersaturation limit. In the vicinity of the superfluid transition the kinetic growth factor exhibits
critical behavior: K ∝ (Tλ−T)ε with the exponent ε=0.743±0.123. A jump in the growth factor is observed at the bcc-hcp transition point. The crystal growth kinetics problem
is solved in the hydrodynamic approximation, explaining both the temperature behavior of K and the existence of the jump in the modification of the crystal structure.
Zh. éksp. Teor. Fiz. 114, 1313–1328 (October 1998) 相似文献
18.
稠密氦气辐射不透明度的实验研究 总被引:1,自引:1,他引:0
用二级氢气炮作为冲击压缩加载工具和多通道瞬态辐射高温计作为主要测量系统,测量了冲击压缩氦气等离子体的光辐亮度历史(初始温度293 K,初始压力为0.6 MPa和1.2 MPa两种).根据实测记录信号波形的有关特征量,计算得到了氦等离子体的光谱吸收系数κ(λ)和冲击压缩铝基板表面的光反射率R.结果发现:受冲击铝基板表面的光反射率~0.4(比其初始反射率0.8约降低一半),与Erskine的数据相同;对于光谱吸收系数的实测数据,本文目前未能给出合理的物理解释. 相似文献
19.
《Current Applied Physics》2018,18(6):762-766
We report a facile method to enhance the critical current density (Jc) of superconducting MgB2 thin films. MgB2 thin films were deposited on zinc acetate dehydrate (Zn(CH3COO)22H2O) spin-coated Al2O3 (000l) substrates by using a hybrid physical-chemical vapor deposition system at low temperatures. Synthesis of MgB2 at low temperatures can reduce the substitution of Zn into the Mg site, hence avoiding the reduction of superconducting critical temperature. MgB2 thin films grown on ZnO-buffered layers showed a significant enhancement of Jc in the magnetic field due to the creation of additional pinning sources, namely point defects and grain boundaries. Broad peaks were observed in the magnetic field dependence of the flux pinning force density, indicating competition of different pinning sources. 相似文献