共查询到20条相似文献,搜索用时 50 毫秒
1.
2.
3.
4.
基于密度泛函理论方法研究分析了一种Zn顶位吸附O的ZnO(110)-O二维膜材料的结构、结合性质、磁性质、电子结构和光吸收性质.结果表明,ZnO(110)二维膜经过O吸附之后,Zn-O键长分别增大到0.1992 nm和0.1973 nm,Zn-O链之间的距离减小到0.5628 nm,O-Zn-O键角度为108.044°,ZnO(110)膜Zn顶位对O原子的吸附为倾斜的吸附.经过Zn顶位O的吸附,ZnO(110)二维膜内原子间离子性结合性增强,吸附的O与Zn也形成偏离子性结合键,Zn顶位吸附O原子之后能量有所降低,吸附体系为反铁磁性材料.O吸附的ZnO(110)-O二维膜为间接带隙型材料,带隙宽度为0.565 eV.材料中的p电子对费米能处态密度贡献较多.ZnO(110)-O二维膜最高吸收峰位于156 nm,吸收率为67181光吸收单位,其在445 nm以上具有宽的强吸收带. 相似文献
5.
6.
7.
为研究HgI2晶体结构缺陷与光吸收的关系,测试了晶体的UV和中红外透过光谱.结果表明,波长约为580 nm时,存在着本征吸收限;波长大于580 nm时,随波长增加,晶体对光的吸收减小,透过率达到45;以上;在1000~2500 nm范围内,UV光谱存在四个明显的光吸收带,对应的入射光能量分别为0.79±0.01 eV,0.72 eV,0.57±0.01 eV 和0.53 eV.中红外透过曲线随波长增加而增大,透过率为39;~68;.通过M/HgI2的I~t曲线,采用简单能级模型进一步确认了生长的HgI2晶体存在0.79±0.01 eV和0.72 eV两个陷阱能级.分析认为,HgI2晶体层间的相对移动形成的结构缺陷造成1572.5 nm(0.79±0.01 eV)和1729.2 nm(0.72 eV)处的吸收,晶体缺碘造成2117.5 nm(0.57±0.01 eV)处的吸收和汞空位造成2305.8 nm(0.53 eV)的吸收.在中红外波段,晶体结构缺陷造成了显著的晶格吸收.严格控制原料的化学计量比有利于减少HgI2晶体的结构缺陷,提高晶体的光学性能. 相似文献
8.
9.
10.
采用大视场光致发光和电致发光实时光谱成像快速检测GaInP/GaAs/GaInP双异质结样品及太阳能电池器件GaAs层中孤立的广延缺陷,并运用不同激光功率对样品进行激发,基于广延缺陷的空间分辨光致发光光谱成像行为探讨了砷化镓中载流子的扩散特性.实验结果表明,当激发光功率密度较小时,由于激发点附近点缺陷的非辐射复合竞争降低了光生载流子的平均寿命,从而使得扩散长度急剧减小.只有当激发光功率密度超过一个阈值使得点缺陷态饱和后,载流子的长距离扩散才能变为可能.此外,根据光激发一维扩散模型求解扩散方程得出对比函数的指数表达形式,并由广延缺陷区域光致发光强度的径向分布导出对比函数值,通过函数拟合估算出砷化镓样品的有效扩散长度. 相似文献
11.
Perylene (PYL) mixed with Behenic acid (BA) and Polymethyl methacrylate (PMMA) separately have been incorporated in the Langmuir-Blodgett film. The surface pressure versus area per molecule area isotherms are measured at various molar ratios. Stability of the mixed monolayer of PYL and BA/PMMA and their collapse pressure are much higher than that of pure PYL. Negligible amount of hysteresis observed in the compression-decompression isotherms indicate the formation of stable monolayer. Miscibility of the mixed systems is found to vary with the film composition. The formation of PYL aggregates in the mixed films is investigated using UV-Vis absorption spectroscopy, emission spectroscopy and atomic force microscopy (AFM). 相似文献
12.
Crystallography Reports - A technique for determining the directions of dislocation lines using an atomic force microscope after selective etching of a single crystal is discussed. The technique... 相似文献
13.
Some observations made on the nature and distribution of monolayer (elementary) steps on the (100) cleavage faces of MgO single crystals by atomic force microscopy are presented and discussed. The following types of patterns of monolayer steps are described: (1) trains of steps, (2) steps terminating on the cleaved surface at the emergence points of screw dislocations, and (3) localized pinning of advancing steps at random sites (probably at the emergence points of edge dislocations). It is shown that: (1) the origins of emergence points of monolayer steps are devoid of hollow cores due to a small Burgers vector of dislocations and (2) the minimum distance between two emerging steps due to screw dislocations and between two pinning centres due to edge dislocations depends on their sign, and is determined by the mutual interaction between neighbouring dislocations. 相似文献
14.
X.N. Jiang D. Xu D.R. Yuan D.L. Sun M.K. Lu G.H. Zhang S.Y. Guo 《Crystal Research and Technology》2001,36(6):601-608
Growth mechanisms and defect formations on {110} faces of cadmium mercury thiocyanate crystals grown at 30°C (σ=0.24) were investigated by using atomic force microscopy (AFM). It was found that, under this condition, spiral dislocation controlled mechanism and 2D nucleation mechanism operates simultaneously and equally during growth, which is completely different from the traditional 2D nucleation and dislocation source controlled mechanisms. A number of 2D nucleus are formed at the large step terraces generated by dislocation sources, leading to the unequal growth rates of the elementary steps and thereby “step bunches” arecaused. Various defects are formed under this growth condition, which is assumed to result from the incongruence between the steps generated by different sources. A new kind of 2D defect, corresponding to one growth layer in height, was observed for the first time. 相似文献
15.
提高膜厚是一种常用的提高YBCO涂层超导体导电能力的方法.如何在提高膜厚的基础上抑制薄膜的临界电流密度(Jc)在外场下的迅速下降是实现YBCO涂层导体产业化的关键.本文选用高钉扎效果的Zr掺杂YBCO复合薄膜进行膜厚和性能关系的研究,在LaAlO3基底上分别通过单次、两次、三次和四次涂覆制备了膜厚分别达200nm(单层膜)、400nm(双层膜)、600nm(三层膜)和800nm(四层膜)的Zr/YBCO复合薄膜,并详细研究了Zr/YBCO复合薄膜在不同膜厚下的微观结构、表面形貌以及超导性能.研究发现,低氟MOD法在重复涂覆制备厚膜的过程中大大节省了时间,提高了制备效率.此外,通过研究YBCO复合膜的厚度和临界电流的关系,得出如下结果:在厚度不超过600 nm的前提下,随着复合膜厚度的增大,其临界电流保持逐渐增加的趋势.其中,单层薄膜的上值最大,达到了3.34 MA/cm2;三层膜的Jc值达到了1.91 MA/cm2,其Ec值最大,达到了每厘米带宽114.6 A. 相似文献
16.
17.
运用溶胶-凝胶法在Si/SiO2/Ti/Pt基底上制备了掺杂不同量的Y3+的单层Ba0.65Sr0.35TiO3 (BST)薄膜和并联结构的BST/ZrO2复合薄膜.研究发现:当BST溶胶中掺入了适量的Y3+后,制备的单层BST的表面形貌得到改善,介电性能提高;掺杂的Y3+为1mol;时单层BST薄膜介电性能最佳,介电常数为400.53;介电损耗为0.0125.BST/ZrO2复合薄膜的电容值相对于单层BST薄膜得到明显提高,当烧结温度为750℃时,BST/ZrO2复合薄膜综合介电性能最佳,介电常数790.12;介电损耗达到0.051. 相似文献
18.
采用热蒸发沉积法,以砷化镓和氧化镓粉末为原料,以氧化铟为催化剂,在800 ℃的氩气气氛中,在(100)砷化镓基片表面上沉积生成GaAs/Ga2O3薄膜.以配有成分分析的场发射扫描电镜(FESEM)、X-射线衍射仪(XRD)、光致发光仪(PL)等测试方法对所得薄膜的成分、形貌、晶体结构和光学性能进行了表征.研究结果表明:薄膜以规整的波浪形均匀地覆盖在砷化镓基片表面上,所得薄膜为GaAs/Ga2O3复合多晶薄膜,光致发光峰为强的红光发射;薄膜的生长机理为固-气-固过程,薄膜中砷元素含量的增加与氧化铟的作用有关. 相似文献
19.
硬质合金是制作金刚石薄膜涂层刀具的重要基体材料,金刚石薄膜在硬质合金基体上的成核、生长及界面特征直接影响其附着强度.本文通过扫描电镜、X射线衍射分析、X射线光电子谱(XPS)及断续切削实验,研究了硬质合金基体含Co量对金刚石薄膜成核、生长及附着强度的影响.研究结果表明,经酸洗处理后,硬质合金基体含Co量对金刚石薄膜成核、生长没有太大影响.但对其附着强度有很大影响.含Co量越高,附着强度越低.酸腐蚀去Co处理后基体表面变得疏松、不连续非金刚石碳界面的存在及热膨胀系数较大是含Co量较高时,附着强度下降的主要原因. 相似文献