Acquisition of Time-Resolved Near-Field Optical Spectrometer for Semiconductor Nanostructure Research

该奖项是为了部分支持将用于top的时间分辨近场光谱仪（TRNFOS）。半导体纳米结构研究。通过结合两种商用仪器，我们可以配置一台光谱仪，它可以实现超快（100 fs）时间分辨率和空间分辨率（500 a），比以前使用最好的远场光学器件实现的分辨率高出一个数量级。该仪器独特的功能组合将使我们能够考虑以前不可能进行的实验。特别是，该仪器将首次允许：(A)不再被不均匀加宽的光致发光线所掩盖的空间局部势涨落的光学观测（遵循Hess等人）(B)在这些空间局部势涨落的约束和散射下的激子动力学研究。(C)量子线和量子点的激子动力学研究。即激子到线和点的空间分辨捕获，以及激子沿线的空间输运。提出的研究的主要方面是研究III-V和II-VI纳米结构。在III-V多量子阱中，TRNFOS仪器的可用性将提供空间分辨率，从而可以通过“固有的”局部电位波动以及通过聚焦离子束混合产生的“外在的”电位来光学观察激子约束到较低维度。对于聚焦离子束混合的情况，该仪器将能够以独特的方式提供由成分混合产生的横向电位分布。这种理解是创造量子线和量子点结构的重要一步。对于量子线状结构，TRNFOS仪器将提供激子寿命和激子各向异性扩散的局部信息，以与我们目前的远场结果进行对比。同样，在II-VI稀释磁异质结构中，该仪器将使我们能够直接观察磁性离子聚集和合金波动对激子动力学和磁性离子本身磁化动力学的影响。我们特别感兴趣的是低维激子磁极化子形成过程中激子自定位的动力学，以及d-d超交换对磁性离子团簇磁化动力学的影响。这台时间分辨近场光谱仪的获得将大大推进目前NSF支持的努力，并为探索半导体材料科学和物理学开辟新的机会。对受限结构、量子线、量子点和阵列的理解将受到这台仪器的强烈影响。＊＊＊

9503853 Jackson This award is for partial support of a time-resolved near-field optical spectrometer (TRNFOS) to be used fop .semiconductor nanostructure research. By combining two commercially available instruments, we can configure a spectrometer that achieves both ultrafast (100 fs) time-resolution and spatial-resolution ( 500 A) more than an order of magnitude better than previously achievable using the best far field optics. The unique combination of capabilities of the instrument will allow us to consider experiments that previously were not possible. In particular, this instrument will allow for the first time: (A) Optical observation of spatially local potential fluctuations no longer masked by the inhomegeneously broadened photoluminescence lines (following Hess et al.) (B) The study of exciton dynamics in confinement to, and scattering from, these spatially local potential fluctuations. (C) The study of exciton dynamics in quantum wires and dots. Namely spatially resolved capture of excitons to wires and dots, as well as spatial transport of excitons along wires. %%% The principal aspects of the proposed research are the study of III-V and II-VI nanostructures. In the III-V multiple quantum wells the availability of the TRNFOS instrument will provide a spatial resolution that will allow optical observation of exciton confinement to lower dimensions through both "intrinsic" local potential fluctuations, as well as "extrinsic" potentials fabricated through focused ion beam mixing. For the case of focused ion beam mixing, the instrument will be capable of providing in a unique manner the lateral potential profile created by compositional intermixing. This understanding is an essential step in creating quantum wire and quantum dot structures. For quantum wire-like structures the TRNFOS instrument will provide local information on exciton lifetimes and exciton anisotropic diffusion to contrast with our p resent far field results. Similarly, in II-VI diluted magnetic heterostructures this instrument will allow us to observe directly the affect of magnetic ion clustering and alloy fluctuations on exciton dynamics and the magnetization dynamics of the magnetic ion themselves. In particular, we are interested in the dynamics of exciton self-localization in the formation of lower dimensional exciton magnetic polarons, and in the affect of d-d superexchange on the magnetization dynamics of magnetic ion clusters. The acquisition of this time-resolved near-field optical spectrometer will significantly advance present NSF supported efforts as well as open new opportunities to explore semiconductor material science and physics. The understanding of confined structures, quantum wires, quantum dots, and arrays will be strongly influenced by the acquisition of this instrument. ***