Acquisition of an Ultrafast Laser System and Near-Field Spectrometer for Investigating II-VI Quantum Dots and for Education

该合同将为采购最先进的时间和空间分辨光谱学系统提供部分支持。该系统将包括两个主要组成部分：(1)飞秒光学参量放大器（OPA）系统，可在240 nm至2.7微米范围内广泛调谐；(2)带驱动电子器件的低温扫描探针（CryoSXM）显微镜。该系统将实现超快（200秒）时间分辨率和亚微米（100至500纳米）空间分辨率。该仪器将用于直接研究局限于自组装CdSe量子点（SAQDs）的激子电子态的性质。我们的团队以及德国和日本的其他团队最近的实验强烈地表明，CdSe点的结构和它们的电子激发与在原型InAs/GaAs量子点中观察到的明显不同。这种差异并不意外，因为II-VI材料作为一个群体更具极性，具有更大的激子效应，更突出的电子-声子相互作用，并且价带偏移明显小于III-V材料。将要进行的研究包括：(i) CdSe点的纳米尺度制图；（ii）时间分辨光致发光激发（PLE）；（iii）单量子点的磁光致发光；时间分辨运输测量；(v)单量子点激子自旋弛豫。使用这些最先进的设备也将为参与这些领域的本科生提供重要的新培训机会。该设备将为研究人员提供显著提高的能力来研究自组装量子点的特性，并在材料研究和技术的一个非常重要的领域培养学生。

9975655JacksonThis award will provide partial support for the acquisition of a state-of-the-art system for temporally- and spatially-resolved optical spectroscopy. This system will involve two main components: (1) A Femtosecond Optical Parametric Amplifier (OPA) systems which is broadly tunable from 240 nm to 2.7 microns, and (2) a low-temperature scanned probe (CryoSXM) microscope with drive electronics. This system will achieve both ultrafast (200 fs) time-resolution and sub-micron (100 to 500 nm) spatial resolution. This instrument will be used to study directly the nature of the electronic states of excitons confined to self-assembled CdSe quantum dots (SAQDs). Recent experiment by our groups and others in Germany and Japan have suggested strongly that the structure of the CdSe dots and their electronic excitations are significantly different than observed in the prototypical InAs/GaAs quantum dots. Such differences are not unexpected as II-VI materials as a group are more polar, with larger excitonic effects, more prominent electron-phonon interactions, and the valence band offsets are significantly smaller than for the III-V materials.Research to be undertaken includes:(i) Nano-scale mapping of the CdSe dots;(ii) Time-resolved Photoluminescence Excitation (PLE); (iii) Magneto-Photoluminescence of Single Quantum Dots; (iv) Time-resolved Transport Measurements; and (v) Exciton Spin-Relaxation of Single Quantum Dots.Acess to this state-of-the-art equipment will also provide significant new training opportunities for undergraduate students participating in these areas.This equipment will provide the investigators with significantly increased capabilities to investigate the properties of self assembled quantum dots, and train students in a very important area of materials research and technology.