共查询到20条相似文献,搜索用时 93 毫秒
1.
2.
一、前 言 无位错硅单晶中的微缺陷严重地影响着大规模集成电路的性能,已引起许多学者的关注和兴趣[1-3],由于微缺陷的应力场很小,目前对直拉硅单晶中微缺陷的观察,主要采用择尤化学腐蚀法、缀饰X射线形貌术、EBIC模式扫描电子显微术、透射电子显微术等.但上述方法的共同缺点是要对样品进行处理.近年来,一些学者采用特殊的X射线双晶形貌方法,对硅单晶原生微缺陷进行观察[4,5],但其设备复杂,实验周期长.我们首次用X射线投影和截面形貌术对不经缀饰的硅单晶原生微缺陷进行了观察,并获得了相应的微缺陷图. 二、实 验 实验用的样品是沿 [100]… 相似文献
3.
从理论上研究了N5B五能级系统中一个激光场重复缀饰四波混频过程.结合能级图分析,从它特殊的Autler-Town分裂峰中可以非常清晰地看出其重复缀饰的作用.还研究了在强Probe场和强耦合场下N5B五能级下缀饰四波混频信号的抑制增强现象.采取独特的处理方法——独立作用法,研究结果表明一个激光场作用于N5B五能级系统时存在两次缀饰,并形成缀饰能级的二重分裂或者三重分裂,不同于多个耦合场对原子的多重缀饰作用.应用于非线性光谱术中对多峰结构的研究.
关键词:
四波混频
电磁感应透明
重复缀饰 相似文献
4.
研究了受强缀饰场作用的五能级原子系统所产生的多波混频共存特性.研究发现,通过调节激光束方向,沿同一方向出射的八波混频、双缀饰四波混频和单缀饰六波混频信号因共用能级的原子相干产生而出现竞争现象,通过控制缀饰场减弱四波混频和六波混频信号强度,可以达到增强八波混频信号的目的.还对级联和并联两种不同缀饰方式下双缀饰四波混频过程的差别进行了详细分析.
关键词:
双缀饰四波混频
单缀饰六波混频
八波混频
抑制增强 相似文献
5.
研究了两电介质面间级联四能级系统原子的缀饰四波混频(FWM)光谱.在缀饰场的作用下FWM信号可产生Autler-Townes (AT)分裂,分裂所产生的峰及凹陷的线型及缀饰场对FWM信号的抑制与增强效应均受原子极化相干及受限原子与光场相互作用瞬态机制的调制. 相似文献
6.
研究了两电介质面间级联四能级系统原子的缀饰四波混频(FWM)光谱.在缀饰场的作用下FWM信号可产生Autler-Townes (AT)分裂,分裂所产生的峰及凹陷的线型及缀饰场对FWM信号的抑制与增强效应均受原子极化相干及受限原子与光场相互作用瞬态机制的调制. 相似文献
7.
研究了薄原子蒸气中Y型四能级系统的双缀饰选择反射光谱(DSR),其线型是三条色散曲线的叠加,其中两条反常色散线型对应于双缀饰电磁感应透明(DEIT).与单光子选择反射光谱(SR)相似,DSR也具有明显的Dicke窄化现象.由于暗态超慢原子的贡献和原子跃迁的量子相干效应,从DSR光谱可观察到显著的群速变慢效应. 相似文献
8.
在YAG:Nd晶体中位错对激光特性的影响 总被引:1,自引:0,他引:1
本文用双折射貌相法和化学腐蚀法测定了六根晶体棒中的位错分布和位错密度,用光学方法检验了晶体的光学质量,晶体的激光性能是在一台Q开关YAG激光装置上测定的。实验表明当位错密度增加到一定程度时,位错形成的应力场会引起明显的双折射,以致探测光通过晶体时波面会发生畸变。在干涉仪上可观察到干涉条纹的增加。同样,在位错应力场区消光比亦下降。因此,作为结构缺陷的位错也是晶体光学不均匀的来源之一。晶体激光性能的实验结果指出:位错对激光输出特性有很大的影响,从激光近场光斑图看出,在位错应力场区,因为高的激光阈值而不能产生激光振荡,并且由于应力双折射效应产生光的退偏性。由于存在高位错密度,晶体的激光发散度增加,倍频效率下降。当晶体中存在缀饰位错(decorated dislocation)时,激光输出特性的变化尤为明显. 相似文献
9.
利用含时量子波包法理论研究了分子在强激光场条件下的量子调控.选取K2分子的三态模型(基态|X〉、激发态|B〉和电离态|X+〉)作为研究对象.在强激光场的作用下,激发态|B〉缀饰成两个子态:|α〉态和|β〉态.分析K2分子电离后的光电子能谱,可以得到缀饰态|α〉和|β〉的能量和概率分布信息.同时,根据分子的缀饰态理论,提出了K2分子的缀饰态选择性分布方案.研究表明:调节激光场的强度可以实现对缀饰态能量的调控,改变激光场的波长可以实现对缀饰态概率的选择性分布. 相似文献
10.
11.
12.
13.
14.
The nucleation of dislocations in single crystals of molybdenum and a Mo-1.5 at % Ir solid solution has been investigated
by nanoindentation. In the curve of indentation of a Berkovich indenter into the single crystals, an abrupt transition from
elastic to plastic deformation has been observed at a depth of 20–40 nm due to the nucleation of dislocations in the initially
dislocation-free region under the contact. Alloying of molybdenum by iridium results in a twofold increase in shear stresses
under which dislocations nucleated in the contact. Therefore, the solid solution impurity of iridium in molybdenum leads to
an increase not only in the plastic strain resistance (to an increase in the hardness) but also in the elastic shear stresses
under which dislocations are generated (homogeneously or heterogeneously) in the contact. The latter effect cannot be explained
only by an increase in the elastic moduli because of its smallness; however, it is determined to a large extent by a higher
degree of perfection of the solid solution crystal as compared to unalloyed molybdenum. 相似文献
15.
E. G. Galieva O. V. Antonova P. E. Panfilov A. N. Titov 《Physics of the Solid State》2011,53(5):1047-1055
The dislocation structure of titanium dichalcogenide single crystals has been investigated. It has been established that the basis of the structure consists of dislocations that lie in the basal plane, are predominantly edge dislocations, and are responsible for the strain behavior of the material. There are also growth dislocations that are predominantly screw dislocations and form dislocation networks. A relationship is revealed between the nature of the chalcogen and the character of the defect structure. 相似文献
16.
C. W. Clawson K. M. Crowe E. E. Haller S. S. Rosenblum J. H. Brewer 《Hyperfine Interactions》1984,18(1-4):603-604
Low-temperature measurements of muonium parameters in various germanium crystals have been performed. We have measured crystals with different levels of neutral impurities, with and without dislocations, and with different annealing histories. The most striking result is the apparent trapping of Mu by silicon impurities in germanium. 相似文献
17.
用AgK_α辐射X射线透射形貌术成功地显示了Nd:YAG晶体中的缺陷性质及其分布.在用引上法及温梯法生长的晶体中存在数种缺陷如生长条纹、沉淀粒子、刃位错、螺应错以及由于位错运动而形成的混合型位错.实验结果与光学方法所得结果相一致,但在判明位错的性质方面,X射线形貌术有其独特的优点. 相似文献
18.
19.
V. V. Malashenko 《Technical Physics》2011,56(9):1287-1290
The effect of a high hydrostatic pressure on the dislocation dipole vibration frequency and the forces of dynamic drag of
dislocations by dislocation dipoles and of dislocation pairs by pinned dislocations is studied. Analytical expressions are
obtained for the force of dynamic drag of mobile dislocation pairs by pinned dislocations and for the force of drag of isolated
dislocations by dislocation dipoles in hydrostatically compressed crystals. Hydrostatic compression leads to a significant
increase in these forces. This effect is most pronounced in alkali-halide crystals, where the drag force increases by a factor
of 1.5–2.0. 相似文献
20.
GENERALIZATION OF ESHELBY'S METHOD TO THE ANISOTROPIC ELASTICITY THEORY OF DISLOCATIONS IN QUASICRYSTALS
下载免费PDF全文
![点击此处可从《物理学报(海外版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The general expressions of the elastic fields induced by straight dislocations in quasicrystals have been given according to Eshelby's method which was used to treat the anisotropic elasticity of dislocations in crystals. As an example, the elastic displacement vector, the stress tensor and the elastic energy density of a screw dislocation line lying on the quasiperiodic plane of decagonal quasicrystals are calculated. 相似文献