共查询到18条相似文献,搜索用时 128 毫秒
1.
2.
3.
在(CdSe)1(ZnSe)3/ZnSe短周期超晶格多量子阱中,根据一维线性链模型计算的结果与实验结果的比较表明,我们在不同的共振条件下分别观察到了来自多量子阱的阱中和垒中ZnSe限制纵光学声子模的Raman散射。与GaAs/AlAs量子阱的偏振选择定则不同,在共振条件下,我们在两种偏振配置下都观察到了阱中ZnSe限制模LO1,并认为这种不同可能来源于样品特殊的电子子带结构和光学声子行为。
关键词: 相似文献
4.
分别应用光致发光、电容电压和深能级瞬态傅里叶谱技术详细研究ZnSe自组织量子点样品的光学和电学行为.光致发光温度关系表明ZnSe量子点的光致发光热猝火过程机理.两步猝火过程的理论较好模拟和解释了相关的实验数据.电容电压测量表明样品表观载流子积累峰出现的深度(样品表面下约100nm处)大约是ZnSe量子点层的位置.深能级瞬态傅里叶谱获得的ZnSe量子点电子基态能级位置为ZnSe导带下的011eV,这与ZnSe量子点光致发光热猝火模型得到的结果一致. 相似文献
5.
分别应用光致发光、电容-电压和深能级瞬态傅里叶谱技术详细研究ZnSe自组织量子点样品的光学和电学行为.光致发光温度关系表明ZnSe量子点的光致发光热猝火过程机理.两步猝火过程的理论较好模拟和解释了相关的实验数据.电容-电压测量表明样品表观载流子积累峰出现的深度(样品表面下约100nm处)大约是ZnSe量子点层的位置.深能级瞬态傅里叶谱获得的ZnSe量子点电子基态能级位置为ZnSe导带下的0.11eV,这与ZnSe量子点光致发光热猝火模型得到的结果一致. 相似文献
6.
在本文中我们首次报道了p型掺杂的自组织Si/Ge量子点中空穴能级子带间的电子拉曼散射,此电子跃迁的能量为105meV。Si/Ge量子点Ge Ge模的共振拉曼散射表明此空穴能级间的电子拉曼散射与Γ点附近的E0(≈2.52eV)发生了共振,而E1的能量小于2.3eV.变温实验和偏振实验进一步证实了我们的指认。所有观测的实验数据与6 bandk·p能带结构理论的计算结果吻合得很好。 相似文献
7.
硫族化镉纳米微晶由于具有发光效率高和发射波长可调谐等优良性质在光电器件中有重要的应用,CdSe/CdS点-棒异质结量子点是典型代表之一。本文中通过非共振拉曼方法探测了该量子点在5~50cm-1的声学声子模,利用不同模式的偏振特性,清晰地指认了球状核壳异质结量子点的扭转模式和径向呼吸模、棒状和点-棒异质结量子点的伸缩模和径向呼吸模等,并观察到了棒状量子点和点-棒异质结量子点的电子拉曼散射。同时发现点-棒异质结量子点的径向呼吸模较尺寸相当的纳米棒量子点发生红移。利用有限元方法形象模拟各量子点声学模的振动形式,并发现点-棒异质结量子点呼吸模振动的局域性。随后,引入局域有效声速的概念,利用改进的Lamb定律,成功解释了该红移是由CdSe核区域声速的减小所导致的,并再次验证该呼吸模局域在核附近区域。该研究对于表征和研究量子点中的限制性声学模具有重要意义,声学模和光学跃迁均局域在量子点附近区域的特性,对调控其激子-声子耦合和相关的光学性质具有重要指导意义。 相似文献
8.
小尺寸Si/Ge量子点内应变和组分的拉曼光谱表征 总被引:1,自引:1,他引:0
本文详细地研究了原始生长和退火处理后的Si/Ge量子点的拉曼光谱。我们观测到了Si/Ge量子点的一系列本征的拉曼振动模以及Ge-Ge模的LO和TO声子峰间4.2cm-1的频率劈裂。通过这些参数,我们自洽地确定了原始生长的平面直径为20nm和高为2nm的Si/Ge量子点内Ge的平均组分为80%,平均应变为-3.4%。分析清楚地表明了这种小尺寸的Si/Ge量子点内的应变仍遵从双轴应变,并且应变的释放主要由量子点和Si隔离层间Si-Ge原子互扩散决定。 相似文献
9.
利用显微荧光和显微拉曼光谱,研究了分子束外延生长的CdSe/ZnSe异质结构中,由两种不同机理形成的两类具有不同尺寸和组分的Zn1-xCdxSe量子岛.4.2 K时的显微荧光光谱表明,当CdSe淀积厚度由1.8 ML增加到2.3ML时,Zn1-xCdxSe量子岛的激子荧光峰有166 meV的较大红移,这是量子岛尺寸改变引起的量子限制势能变化所不能完全解释的.经过对样品的显微荧光和显微拉曼光谱的对比分析,发现还存在另外两种引起量子岛荧光峰较大红移的机理:一方面是因为随着CdSe淀积厚度的增加,具有更低能态的大岛密度的增加,并逐渐取代小岛而主导Zni-xCdxSe量子岛的荧光性质;另一方面是由于CdSe/ZnSe量子结构中的两类量子岛的Cd组分浓度也会随CdSe淀积厚度的增加而增加,从而引起量子岛荧光峰的较大红移. 相似文献
10.
量子点(QD)照明器件中电流导致的焦耳热会使其工作温度高于室温,因此研究量子点的发光热稳定性十分重要。本文利用稳态光谱和时间分辨光谱研究了具有不同壳层厚度的Mn掺杂ZnSe(Mn: ZnSe)量子点的变温发光性质,温度范围是80~500 K。实验结果表明,厚壳层(6.5单层(MLs))Mn: ZnSe量子点的发光热稳定性要优于薄壳层(2.6 MLs)的量子点。从80 K升温到400 K的过程中,厚壳层Mn: ZnSe量子点的发光几乎没有发生热猝灭,发光量子效率在400 K高温下依然可以达到60%。通过对比Mn: ZnSe量子点的变温发光强度与荧光寿命,对Mn: ZnSe量子点发光热猝灭机制进行了讨论。最后,为了研究Mn: ZnSe量子点的发光热猝灭是否为本征猝灭,对具有不同壳层厚度的Mn: ZnSe量子点进行了加热-冷却循环(300-500-300 K)测试,发现厚壳层的Mn: ZnSe量子点的发光在循环中基本可逆。因此,Mn: ZnSe量子点可以适用于照明器件,即使器件中会出现不可避免的较强热效应。 相似文献
11.
ZnSe/semi‐insulating GaAs interfaces were studied by observing photogenerated plasmon–LO (PPL) coupled modes by nonresonant micro‐Raman spectroscopy. The effect of the carriers generated by the focused laser beam was investigated for a series of different thicknesses of ZnSe epitaxial layers. The PPL mode in GaAs was observed in the micro‐Raman spectra for all samples, but with different magnitude. The plasma is believed to be an electron gas as a result of the negative nature of the interfacial region that contains predominantly hole traps. The free carrier concentration is estimated to be > 1018 cm−3 and their lifetime ∼0.1 ns. This relatively long lifetime suggests that the ZnSe/GaAs interface has to be of high structural quality leading to a low recombination velocity. ZnSe/GaAs heterostructures of less crystalline quality (as determined by resonant Raman measurements) shows the effect of photogenerated carriers only to lesser extent. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
12.
13.
I. I. Reshina S. V. Ivanov V. A. Kosobukin S. V. Sorokin A. A. Toropov 《Physics of the Solid State》2003,45(8):1579-1585
Raman scattering in a number of BeTe/ZnSe type-II superlattices which share no common cations or anions in the interfaces was studied. Folded acoustic phonons; LO phonons of the first, second, and third order in the ZnSe layers; and Kliewer-Fuchs-type electrostatic interface phonons were observed when excited in resonance with the direct exciton transition in the ZnSe layers. Nonresonant excitation produced LO phonons in the ZnSe and BeTe layers and a high-frequency mechanical interface mode, assigned tentatively to a local vibration of the interface Be-Se bond. 相似文献
14.
15.
Nanocomposites of
poly[(2-methoxy,5-octoxy)1,4-phenylenevinylene]-zinc selenide
(MOPPV-ZnSe) are synthesized by mixing the polymerization of 1,4-bis
(chloromethyl)-2-methoxy-5-octoxy-benzene in the presence of ZnSe
quantum dots. The resulting MOPPV-ZnSe nanocomposites possess a
well-defined interfacial contact, thus significantly promoting the
dispersion of ZnSe within the MOPPV matrix and facilitating the
electronic interaction between these two components. Raman and
UV--visible absorption spectra are influenced by the incorporation
of ZnSe nanocrystals. High-resolution transmission electron
microscopic and tapping-mode atomic force microscopic results show
clearly the evidence for phase-segregated networks of ZnSe
nanocrystals, which provide a large area of interface for charge
separation to occur. Steady-state spectra of MOPPV-ZnSe
nanocomposites are markedly quenched by the introduction of intimate
polymer/ZnSe junctions. Time-resolved photoluminescence
measurements show that the lifetime decays quickly, which further
confirms the occurrence of charge transfer in MOPPV-ZnSe
nanocomposites. 相似文献
16.
Raman spectra in superlattices composed of layers of self-assembled CdTe quantum dots separated by ZnTe barriers are investigated. As the barrier thickness increases, a high-frequency shift of all peaks is observed, which is explained by a decrease in the lattice constant averaged over the volume of the entire structure. Peaks are found at a CdTe TO mode frequency of 140 cm?1 and also at 120 cm?1. The first peak is assigned to the symmetric Coulomb (interface) mode of the quantum dot material, and the low-frequency peak is assigned to the symmetric mode of the phonons captured in the quantum dot. This combination of modes in structures with quantum dots has not been observed previously. 相似文献
17.
18.
关于半导体极薄层超晶格拉曼散射特征的研究杨昌黎,张树霖(北京大学物理系北京100871)R.Planel(LaboratiredeMtcrostructusedetdeMicroelectroniqueCentreNationaldelaRecher... 相似文献