首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   33篇
  免费   1篇
化学   5篇
晶体学   4篇
力学   1篇
物理学   24篇
  2018年   2篇
  2015年   3篇
  2014年   2篇
  2012年   5篇
  2011年   2篇
  2010年   1篇
  2009年   5篇
  2006年   5篇
  2005年   4篇
  2004年   3篇
  2003年   1篇
  1996年   1篇
排序方式: 共有34条查询结果,搜索用时 27 毫秒
1.
The magnetoresistance of a TbTe3 two-dimensional conductor with a charge-density wave (CDW) has been measured in a wide temperature range and in magnetic fields of up to 17 T. At temperatures well below the Peierls transition temperature and in high magnetic fields, the magnetoresistance exhibits a linear dependence on the magnetic field caused by the scattering of normal charge carriers by “hot” spots of the Fermi surface. In the sliding CDW regime in low magnetic fields, a qualitative change in the magnetoresistance has been observed associated with the strong scattering of carriers by the sliding CDW.  相似文献   
2.
InAsSb-based nBn photodetectors were fabricated on GaAs, using the interfacial misfit (IMF) array growth mode, and on native GaSb. At −0.1 V operating bias, 200 K dark current densities of 1.4 × 10−5 A cm2 (on GaAs) and 4.8 × 10−6 A cm−2 (on GaSb) were measured. At the same temperature, specific detectivity (D*) figures of 1.2 × 1010 Jones (on GaAs) and 7.2 × 1010 Jones (on GaSb) were calculated. Arrhenius plots of the dark current densities yielded activation energies of 0.37 eV (on GaAs) and 0.42 eV (on GaSb). These values are close to the 4 K bandgap of the absorption layers (0.32–0.35 eV) indicating diffusion limited dark currents and small valence band offsets. Significantly, these devices could be used for mid-infrared focal plane arrays operating within the temperature range of cost-effective thermoelectric coolers.  相似文献   
3.
Vanadium oxide micro and nanosized rods were grown using pulsed laser deposition technique under different oxygen pressures. X-ray diffractogram shows a predominant mixture of vanadium dioxide, VO2 and Magneli phase, V3O7. The diameters of the rods were found to increase from 300 nm to 2.3 μm with increase in oxygen pressure from 0.1 mbar to 0.5 mbar as seen from high resolution scanning electron microscope images. Raman spectra of the rods show peaks at all the characteristic vibrations corresponding to that of V Ox phase. The 0.5 mbar oxygen deposited sample shows a semiconducting behavior from 300 to 77 K and is paramagnetic down to 5 K. Using versatile pulsed laser deposition we have established the tunability of the dimensions of V Ox nanorods which can find numerous potential applications in electrochemistry, catalysis, etc.  相似文献   
4.
Ring-opening suspension polymerization of p-dioxanone(PDO) in supercritical carbon dioxide(scCO2) was investigated in the presence of poly(caprolactone)-perfluropolyether-poly(caprolactone)(PCL-PFPE-PCL).The molecular weight,yield and particle morphology of poly(p-dioxanone)(PPDO) were studied.The stabilizer was effective to stabilize the ring-opening polymerization(ROP) of PDO in scCO2,leading to the formation of resorbable microparticles in a"one pot"procedure.The mean size of PPDO microparticles obtained from suspension polymerizations was sensitive to the rate of agitation and the stabilizer concentration.The method to generate PPDO microparticles has overcome its unprocessable drawback with common organic solvents and provided new product form for biomedical applications.  相似文献   
5.
染料敏化太阳电池工艺参数的优化   总被引:1,自引:1,他引:0  
染料敏化纳晶TiO2薄膜太阳电池的性能受TiO2浆料组成、薄膜厚度、烧结工艺、染料浸渍时间、导电玻璃类型以及电极处理工艺等因素影响是很明显的.通过对上述各工艺参数的研究,探讨了它们对电池性能的影响规律,获得了最佳的工艺参数组合.  相似文献   
6.
The gyromagnetic properties of ferrite materials and the nonreciprocal property of a silicon-ferrite photonic crystal cavity are investigated in the terahertz region. Through the structure optimization and analysis of defect mode coupling, we design a magnetically tunable circulator, of which central operating frequency can be tuned from 180 to 205 GHz and the maximum isolation is 65.2 dB. Moreover, the further study shows that the gyrotropy, dispersion, and ferromagnetic loss of ferrite materials under the different external magnetic fields greatly affect the transmission and isolation property of this device. This circulator is flexible to realize functions of controllable splitting, routing, filtering and isolation by changing the external magnetic field for the THz applications.  相似文献   
7.
杨春  余毅  李言荣  刘永华 《物理学报》2005,54(12):5907-5913
构建了一个ZnO沉积在α-Al2O3(0001)表面生长初期的模型,采用基于密度泛函理论的平面波超软赝势法进行了动力学模拟.发现在400,600和800℃的条件下界面原子有不同的扩散能力,因此温度对ZnO/α-Al2O3(0001)表面界面结构以及ZnO薄膜生长初期模式有决定性的影响.在整个ZnO吸附生长过程中,O原子的扩散系数大于Zn原子的扩散系数,O原子的层间扩散对薄膜的均匀生长起着重要作用.进一步从理论计算上证实了ZnO在蓝宝石(0001)上两种生长模式的存在,400℃左右生长模式主要是Zn螺旋扭曲生长,具有Zn六角平面对称特征,且有利于Zn原子位于最外表面.600℃左右呈现为比较规则的层状生长,且有利于O原子位于最外表面.模拟观察到在ZnO薄膜临近Al2O3基片表面处,Zn的空位缺陷明显多于O的空位缺陷. 关键词: 扩散 薄膜生长 2O3(0001)')" href="#">α-Al2O3(0001) ZnO  相似文献   
8.
 Incorporation of phosphorus into silicon from a spin-on dopant layer (SOD) at 400 °C is described. Annealing experiments were carried out with SOD films deposited on (100) silicon substrates by using the spin-on technique. Conventional heating on a hotplate in normal atmosphere and a temperature range up to 400 °C was used to study the dopant incorporation. After removing the SOD-films one part of the silicon substrates was annealed at higher temperatures. Investigations were carried out by SIMS, SAM, XPS, HTEM, stripping Hall and Van der Pauw measurements before and after the high temperature annealing. Chemical phosphorus concentration profiles obtained from low temperature annealed samples showed diffusion depths of 60–80 nm (extrapolated to a substrate doping level of 1016 cm-3) and surface concentrations of 1019–1020 cm-3. Electron concentration profiles exhibiting maximum values around 2⋅1019 cm-3 could be measured on high temperature annealed samples only. Received: 28 March 1996/Accepted: 19 August 1996  相似文献   
9.
Plasma-enhanced chemical vapor deposition (PECVD) method was employed to grow the Fe-catalyzed carbon nanotubes (CNTs). The grown CNTs with a uniform diameter in the range of about 10-20 nm and the typical lengths beyond 1 μm resulted in a very high aspect ratio. The Raman and TEM results showed that the grown CNTs contained a large amount of carbonaceous particles and crystal defects, such as pentagon-heptagon pair defects. XPS measurement indicated that the CNTs had CH covalent bonds. Field emission characteristics exhibited the low turn-on threshold field of 2.75 V/μm and the maximum emission current density of 7.75 mA/cm2 at 6.5 V/μm. The growth mechanism of CNTs and the effects of hydrogen plasma on their structure were discussed.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号