NER: Enhanced Magnetoabsorption Oscillations in Semiconductor Nanorings

这是一个纳米级探索性研究(NER)奖，由提交给纳米科学与工程(NSE)倡议的一项提案资助。这项理论研究的重点是基于最近发展的制造能力的本征环形半导体纳米结构(称为纳米环)可能提供的新现象和由此产生的功能。在前期的工作中，我们预测了纳米环在静电场或高频电场存在的情况下应该表现出灵敏的磁光特性，因为贯穿纳米环的磁通是不同的。在1-10KV/cm的直流电场(与施加在整个结构上的~1V电位一致)的情况下，与~0.1Tesla的磁场变化相关的光谱特征是明显的。这种磁场灵敏度比通常与量子井中的磁激子有关的灵敏度要高得多，在量子井中，通常需要超过一特斯拉的磁场才能影响明显的光谱变化。此外，与类似的输运现象不同的是，这些磁光现象预计将在高达数十凯尔文的温度下发生。这为纳米环中中性激子的Aharonov-Bohm效应提供了潜在的灵敏光学探针，其中磁吸收随穿线通量周期性地变化，周期由电子通量量子Hc/e给出。Aharonov-Bohm效应在半导体纳米环的光学性质中的理论和实验证明，进一步推动了对传统上属于输运领域的相关现象的探索。我们已经开始研究无序的影响，着眼于可能的Al‘tschuler-Aronov-Spivak振荡，其周期Hc/2e是电子通量量子的一半。此外，类似于普遍电导波动的效应很可能在激子共振的频率附近观察到。与传输测量相比，这种光学研究提供了更好的频率和波矢选择性，而在传输测量中，这些参数的控制是有限的。这些研究将确定利用这种效应的器件的可行性，并为相关问题提供理论基础。这项研究在物理学和工程学的几个领域都具有基础和应用价值。这项工作将与德国和瑞士的团体合作进行，此外还有佐治亚理工学院。%这是纳米级探索性研究(NER)奖，由提交给纳米科学与工程(NSE)倡议的一项提案资助。这项理论研究的重点是基于最近发展的制造能力的本征环形半导体纳米结构(称为纳米环)可能提供的新现象和由此产生的功能。在前期的工作中，我们预测了纳米环在静电场或高频电场存在的情况下应该表现出灵敏的磁光特性，因为贯穿纳米环的磁通是不同的。这些研究将确定器件利用这一效应的可行性，并为相关问题提供理论依据。这项研究在物理学和工程学的几个领域都具有基础和应用价值。除了佐治亚理工学院，这项工作还将与德国和瑞士的团体合作进行。

This is a Nanoscale Exploratory Research (NER) award that is funded as a result of a proposal submitted to the Nanoscience and Engineering (NSE) initiative. This theoretical research focuses on new phenomena and the resulting functionalities that may be afforded by intrinsic ring-shaped semiconductor nanostructures, called nanorings, based on recently developed fabrication capabilities. In preliminary work, we have predicted that nanorings should exhibit sensitive magneto-optical characteristics in the presence of a static or high-frequency electric field as a magnetic flux threading an intrinsic nanoring is varied. Spectroscopic signatures associated with magnetic field changes of ~0.1 Tesla are evident in the presence of dc electric fields on the order of 1-10kV/cm (consistent with ~1 V potential applied across the structure). The magnetic-field sensitivity is considerably superior to that typically associated with magnetoexcitons in quantum wells where magnetic fields in excess of one Tesla is often needed to affect an appreciable spectroscopic change. Moreover, unlike the analogous transport phenomena, these magneto-optical phenomena are predicted to occur at temperatures up to several tens of Kelvins.This provides a potentially sensitive optical probe of the Aharonov-Bohm effect of neutral excitons in nanorings, in which the magnetoabsorption varies periodically with the threading flux, the period being given by the electron flux quantum hc/e. The demonstration - both theoretical and experimental - of the Aharonov-Bohm effect in the optical properties of semiconductor nanorings, moreover, spurs the search for related phenomena that have traditionally been in the domain of transport. We have begun work investigating the effects of disorder, with an eye on possible Al'tschuler-Aronov-Spivak oscillations, whose period hc/2e is half the electron flux quantum. In addition, effects analogous to universal conductance fluctuations are likely to be observable in the frequency vicinity of an excitonic resonance. Such optical studies allow for superior frequency and wavevector selectivity compared with transport measurements where there is limited control of these parameters.The studies will determine the feasibility of devices exploiting this effect and provide a theoretical basis for related problems. This research is both of fundamental and applied interest across several fields of physics and engineering. The work will be carried out in collaboration with groups in Germany and Switzerland, in addition to Georgia Tech.%%%This is a Nanoscale Exploratory Research (NER) award that is funded as a result of a proposal submitted to the Nanoscience and Engineering (NSE) initiative. This theoretical research focuses on new phenomena and the resulting functionalities that may be afforded by intrinsic ring-shaped semiconductor nanostructures, called nanorings, based on recently developed fabrication capabilities. In preliminary work, we have predicted that nanorings should exhibit sensitive magneto-optical characteristics in the presence of a static or high-frequency electric field as a magnetic flux threading an intrinsic nanoring is varied. The studies will determine the feasibility of devices exploiting this effect and provide a theoretical basis for related problems. This research is both of fundamental and applied interest across several fields of physics and engineering. The work will be carried out in collaboration with groups in Germany and Switzerland, in addition to Georgia Tech.***