Moskalenko Evgenii S, Larsson L Arvid, Larsson Mats, Holtz Per Olof, Schoenfeld Winston V, Petroff Pierre M
Department of Physics, Chemistry and Biology (IFM), Linkoping University, S-581 83 Linkoping, Sweden, A. F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021, Polytechnicheskaya 26, St. Petersburg, Russia.
Nano Lett. 2009 Jan;9(1):353-9. doi: 10.1021/nl803148q.
We report on magneto-photoluminescence studies of InAs/GaAs quantum dots (QDs) of considerably different densities, from dense ensembles down to individual dots. It is found that a magnetic field applied in Faraday geometry decreases the photoluminescence (PL) intensity of QD ensembles, which is not accompanied by the corresponding increase of PL signal of the wetting layer on which QDs are grown. The model suggested to explain these data assumes considerably different strengths of suppression of electron and hole fluxes by a magnetic field. This idea has been successfully checked in experiments on individual QDs, where the PL spectra allow to directly monitor the charge state of a QD and, hence, to conclude about relative magnitudes of electron and hole fluxes toward the QD. Comparative studies of different individual QDs have revealed that the internal electric field in the sample (which was altered in the experiments in a controllable way) together with an external magnetic field will determine the charge state and emission intensity of the QDs.
我们报告了对密度差异很大的InAs/GaAs量子点（QD）进行的磁光致发光研究，从密集的量子点集合到单个量子点。研究发现，以法拉第几何结构施加的磁场会降低量子点集合的光致发光（PL）强度，而这并未伴随着量子点生长其上的润湿层PL信号的相应增加。为解释这些数据而提出的模型假定磁场对电子和空穴通量的抑制强度有很大差异。这一想法已在对单个量子点的实验中得到成功验证，在这些实验中，PL光谱能够直接监测量子点的电荷状态，从而推断出流向量子点的电子和空穴通量的相对大小。对不同单个量子点的比较研究表明，样品中的内部电场（在实验中以可控方式改变）与外部磁场将共同决定量子点的电荷状态和发射强度。
