全文获取类型
收费全文 | 93篇 |
免费 | 65篇 |
国内免费 | 4篇 |
专业分类
化学 | 7篇 |
晶体学 | 9篇 |
物理学 | 146篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 8篇 |
2015年 | 2篇 |
2014年 | 8篇 |
2013年 | 7篇 |
2012年 | 7篇 |
2011年 | 19篇 |
2010年 | 4篇 |
2009年 | 7篇 |
2008年 | 7篇 |
2007年 | 14篇 |
2006年 | 14篇 |
2005年 | 6篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 7篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 1篇 |
排序方式: 共有162条查询结果,搜索用时 203 毫秒
41.
用多模干涉原理分析和设计了光通信波长(1.30μm~1.55μm)的Si1-xGex/Si滤波器,并用模的传播分析方法对其传输特性进行了研究。结果发现,在Ge含量x=0.04时,干涉区的脊高和宽度分别为6.35μm和8μm。如果多模干涉区长度LM=2302.5μm,可滤1.30μm而通1.55μm的波长。且具有31dB的对比度和0.01dB的插入损耗;如果多模干涉区长度LM=2512.5μm,可滤1.55μm而通1.30μm的波长。具有16dB的对比度和0.09dB的插入损耗。 相似文献
42.
F. Gao D. D. Huang J. P. Li Y. X. Lin M. Y. Kong J. M. Li Y. P. Zeng L. Y. Lin 《Journal of Crystal Growth》2000,220(4):457-460
Three n–p–n Si/SiGe/Si heterostructures with different layer thickness and doping concentration have been grown by a home-made gas source molecular-beam epitaxy (GSMBE) system using phosphine (PH3) and diborane (B2H6) as n-and p-type in situ doping sources, respectively. Heterojunction bipolar transistors (HBTs) have been fabricated using these structures and a current gain of 40 at 300 K and 62 at 77 K have been obtained. The influence of thickness and doping concentration of the deposited layers on the current gain of the HBTs is discussed. 相似文献
43.
本文设计了一种通过在版图布局中引入伪集电极的方法来提高锗硅异质结双极晶体管(SiGe HBT)抗单粒子性能的方法. 利用半导体器件模拟工具, 针对加固前后的SiGe HBT开展了单粒子效应仿真模拟, 分析了伪集电极对SiGe HBT电荷收集机理的影响. 结果表明, 引入的伪集电极形成的新的集电极-衬底结具有较大的反偏能力, 加固后SiGe HBT伪集电极通过扩散机理, 大量收集单粒子效应产生的电荷, 有效地减少了实际集电极的电荷收集量, 发射极、基极电荷收集量也有不同程度的降低, 加固设计后SiGe HBT 的单粒子效应敏感区域缩小, 有效的提高了SiGe HBT 器件抗单粒子效应辐射性能. 此项工作的开展为SiGe HBT电路级单粒子效应抗辐射加固设计打下良好的基础. 相似文献
44.
Hidehiro Suzuki Noritaka Usami Akiko Nomura Toetsu Shishido Kazuo Nakajima Takashi Suemasu 《Journal of Crystal Growth》2010,312(22):3257-3260
We investigated the impact of an amorphous Ge (a-Ge) thin layer inserted at the amorphous Si (a-Si)/Al interface on Al-induced crystallization. In situ observation of the growth process clarified that the nucleation rate is drastically reduced by insertion of a-Ge, which led to increase in the average size of crystal grains. This was interpreted as resulting from decrease in the driving force of crystallization, mainly due to the larger solubility of Ge in Al than that of Si in Al. The obtained films were SiGe alloys with lateral distribution of Ge content, and its origin is discussed based on the two-step nucleation process. 相似文献
45.
Y. Bogumilowicz J.M. Hartmann C. Di Nardo P. Holliger A.-M. Papon G. Rolland T. Billon 《Journal of Crystal Growth》2006,290(2):523-531
We have first of all studied (in reduced pressure–chemical vapour deposition) the high-temperature growth kinetics of SiGe in the 0–100% Ge concentration range. We have then grown very high Ge content (55–100%) SiGe virtual substrates at 850 °C. We have focused on the impact of the final Ge concentration on the SiGe virtual substrates’ structural properties. Polished Si0.5Ge0.5 virtual substrates were used as templates for the growth of the high Ge concentration part of such stacks, in order to minimize the severe surface roughening occurring when ramping up the Ge concentration. The macroscopic degree of strain relaxation increases from 99% up to values close to 104% as the Ge concentration of our SiGe virtual substrates increases from 50% up to 100% (discrepancies in-between the thermal expansion coefficients of Si and SiGe). The surface root mean square roughness increases when the Ge concentration increases, reaching values close to 20 nm for 100% of Ge. Finally, the field (the pile-up) threading dislocations density (TDD) decreases as the Ge concentration increases, from 4×105 cm−2 (1–2×105 cm−2) for [Ge]=50% down to slightly more than 1×105 cm−2 (a few 104 cm−2) for [Ge]=88%. For [Ge]=100%, the field TDD is of the order of 3×106 cm−2, however. 相似文献
46.
A novel type of optical element for synchrotron radiation applications in the X‐ray region: namely laterally‐graded aperiodic crystals on the basis of Si1‐xGex mixed crystal is presented. The lattice parameter of such gradient crystals containing up to some at. % Ge changes nearly linearly along the plane of diffraction. Thus the variation of the Bragg angle of divergent incident light on the crystal can be compensated. This opens up the possibility to operate a crystal monochromator in nearly crystal limited resolution in the whole energy range above 2 keV at the full vertical synchrotron source divergence without a collimating pre‐mirror. Simultaneously the reflected spectral intensity can be increased considerably as compared with a conventional Si‐crystal monochromator. 相似文献
47.
48.
In the present paper the electroluminescence of PIN diodes with either strained SiGe/Si or Ge islands in the i-region has been investigated experimentally and by quantitative modelling. The modelling helped to improve the diode structure. Consequently, diodes with strained Si0.80Ge0.20 could be improved so as to reveal emission up to room temperature, if the thickness was high enough. To overcome the thickness limitation due to plastic relaxation, we used selective epitaxy on small areas. We also present results for diodes with Ge islands in the active region. The internal quantum efficiency of light emitting diodes with strained SiGe was at room temperature 10−4, while diodes with islands emitted ten times less light. 相似文献
49.
The stress effect of SiGe pMOSFETs has been investigated to understand the electrical properties of devices fabricated on the Si bulk and PD SOI substrates. A comparison of the drain saturation current (ID.sat) and maximum transconductance (gm,max) in both the SiGe bulk and the SiGe PD SOI devices clearly shows that the SiGe PD SOI is more immune from hot-carriers than the SiGe bulk. The stress-induced leakage current (SILC) is hardly detectable in ultra-thin oxide, because the increasing contribution of direct tunneling is comparable to the trap-assisted component. The SiGe PD SOI revealed degraded properties being mainly associated with the detrimental silicon-oxide interface states of the SOI structure. 相似文献
50.
硅锗异质结双极晶体管(SiGe HBT)一般以重掺硼(B)的应变SiGe层作为基区.精确表征SiGe材料能带结构对SiGe HBT的设计具有重要的意义.在应变SiGe材料中,B的重掺杂一方面会因为重掺杂效应使带隙收缩,另一方面,B的引入还会部分补偿Ge引起的应变,从而改变应变引起的带隙变化.在重掺B的应变SiGe能带结构研究中,采用半经验方法,考虑了B的应变补偿作用对能带的影响,对Jain-Roulston模型进行修正,并分析了重掺杂引起的带隙收缩在导带和价带的分布. 相似文献