共查询到19条相似文献,搜索用时 78 毫秒
1.
2.
采用LP-MOVPE技术,在(001)InP衬底上生长的InAs/InP自组装量子点是无序的。为了解决这个问题,在InP衬底上先生长张应变的GaAs层,然后再生长InAs层,可得到有序化排列的量子点。本文对张应变GaAs层引入使量子点有序化排列的机理进行了分析,为生长有序化、高密度,均匀性好自组装量子点提供了依据。 相似文献
3.
4.
5.
我们利用气态源分子束外延设备在不同In组分的InGaP或InAlP虚衬底上生长Ge薄膜,并比较不同虚衬底上Ge薄膜的材料性质。利用拉曼光谱方法测得生长在InGaP虚衬底上的Ge薄膜最大的张应变量可达1.8%,而生长在InAlP虚衬底上的最大张应变量可达2.0%。通过对表面Ge进行腐蚀并测试电阻的方法,我们发现Ge生长在InGaP上存在平行导电问题,而Ge生长在InAlP上则可以消除平行导电的影响。通过霍尔测试验证了Ge受到张应变时对电子迁移率的提高作用。 相似文献
6.
7.
8.
9.
10.
11.
采用超高真空化学气相淀积系统制备了小尺寸、高密度、纵向自对准的Ge量子点.通过TEM和AFM对埋层和上层量子点的形貌和尺寸分布进行了研究,对生长的温度和时间进行了优化.采用硼预淀积的方法得到了尺寸分布小于3%的均匀的圆顶形Ge量子点.采用低温光荧光测量了多层量子点的光学特性.在10K的PL谱可以观察到明显的蓝移现象,表明量子点中较强的量子限制效应.量子点非声子峰的半高宽约为46meV,表明采用UHV/CVD工艺生长的多层量子点具有较窄的尺寸分布. 相似文献
12.
采用原位成核掺杂法合成了Li、Zn金属离子掺杂的InP量子点(分别记为Li: InP和Zn: InP), 并研究了掺杂剂对量子点的结构、尺寸和光学性能的影响。研究结果表明, Li+、Zn2+掺杂的InP量子点结晶度较高且尺寸均匀。虽然Li+掺杂未引起InP量子点的结构发生变化, Li+未进入InP晶格, 但是抑制了InP量子点的成核与长大, 使其吸收谱和荧光谱均发生大幅度的蓝移。Zn掺杂同样也抑制InP量子点的成核与长大, 并且形成InP/Zn3P2/ZnO复合核壳结构, 显著增强了InP量子点的荧光, 尤其是当Zn掺杂浓度(Zn/In原子比)为0.2时, InP量子点的荧光强度增加近100多倍, 这对短波长InP量子点的合成具有一定的参考价值。 相似文献
13.
Philipp Stadler Shaimaa A. Mohamed Jacek Gasiorowski Mykhailo Sytnyk Sergii Yakunin Markus C. Scharber Christina Enengl Sandra Enengl Daniel A. M. Egbe Mabrouk K. El‐Mansy Salah S. A. Obayya N. Serdar Sariciftci Kurt Hingerl Wolfgang Heiss 《Advanced materials (Deerfield Beach, Fla.)》2015,27(9):1533-1539
14.
首次采用固相外延生长技术在Si(001)表面直接生长Sn量子点,并应用原子力显微镜(AFM)、X射线衍射(XRD)和同步辐射傅里叶红外光谱(FTIR)研究了退火条件对量子点样品的表面形貌、结晶性和红外光学性质的影响.AFM结果表明,随着退火温度的升高和退火时间的延长,量子点的平均尺寸变大,面密度减小.XRD结果显示,外延得到的Sn量子点为四方结构的β-Sn,与衬底的相对取向为Sn(110)//Si(001).由于β-Sn量子点的尺寸仍较大,同步辐射FTIR谱中没有观察到量子点的特征吸收峰. 相似文献
15.
采用高温熔融-退火法在钠硼铝硅酸盐(SiO2-B2O3-Na2O-Al2O3-ZnO-AIF3-Na2O)玻璃中生长了PbSe量子点,通过X射线衍射(XRD)、透射电镜(TEM)、光致荧光(PL)谱等研究了玻璃配料中不同ZnO含量对PbSe量子点尺寸和浓度的影响,结果表明,ZnO含量占总玻璃配料质量比约9.4%时,生成的量子点尺寸比较均匀,直径约为6.5nm,且浓度较高,PL谱强度最强,辐射峰位于1790nm,FWHM为296nm。玻璃配料中加入适量的ZnO有助于PbSe量子点的形成,减少Se元素的挥发,使玻璃中的量子点尺寸分布趋于均-化。 相似文献
16.
17.
Honeycombs are widely used in aerospace structures due to their low density and high specific strength. In this paper, effective electromagnetic properties of irregular honeycombs are investigated, by using the three dimensional homogenization theory and corresponding computational procedure. This homogenization method, being the extension of two-scale asymptotic approach, is employed to determine the expressions of the effective dielectric permittivity, magnetic permeability and electrical conductivity. To verify and validate the proposed model and procedure, effective permittivities of a typical irregular honeycomb are studied and compared with those of semi-empirical formulae. Moreover, the effect of geometry of honeycomb's unit cell on effective permittivities is also examined. Compared to semi-empirical estimations, the two-scale asymptotic homogenization method can be used to achieve more accurate results of effective electromagnetic properties for honeycombs in the scope of numerical modeling, and it can be also extended for estimation of effective electromagnetic tensors for various periodic composites. 相似文献
18.
Xingchen He Yanliang Liu Christopher J. Butch Bo Ram Lee Feng Guo Jiangxiao Wu Ziyang Wang Qian Lu Jung Hyun Jeong Yiqing Wang Sung Heum Park 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(44)
Here, a simplified synthesis of graphitic carbon nitride quantum dots (g‐C3N4‐QDs) with improved solution and electroluminescent properties using a one‐pot methylamine intercalation–stripping method (OMIM) to hydrothermally exfoliate QDs from bulk graphitic carbon nitride (g‐C3N4) is presented. The quantum dots synthesized by this method retain the blue photoluminescence with extremely high fluorescent quantum yield (47.0%). As compared to previously reported quantum dots, the g‐C3N4‐QDs synthesized herein have lower polydispersity and improved solution stability due to high absolute zeta‐potential (?41.23 mV), which combine to create a much more tractable material for solution processed thin film fabrication. Spin coating of these QDs yields uniform films with full coverage and low surface roughness ideal for quantum dot light‐emitting diode (QLED) fabrication. When incorporated into a functional QLED with OMIM g‐C3N4‐QDs as the emitting layer, the LED demonstrates ≈60× higher luminance (605 vs 11 Cd m?2) at lower operating voltage (9 vs 21 V), as compared to the previously reported first generation g‐C3N4 QLEDs, though further work is needed to improve device stability. 相似文献