Optical spin polarization in double charged InAs self‐assembled quantum dots
Optical spin polarization in double charged InAs self‐assembled quantum dots
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DOI：
10.1002/pssa.200460324
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发表时间：
2005-02
期刊：
影响因子：
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通讯作者：
V. Kalevich;I. Merkulov;A. Shiryaev;K. Kavokin;M. Ikezawa;T. Okuno;P. Brunkov;A. Zhukov;V. Ustinov;Y. Masumoto
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文献类型：
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作者：
V. Kalevich;I. Merkulov;A. Shiryaev;K. Kavokin;M. Ikezawa;T. Okuno;P. Brunkov;A. Zhukov;V. Ustinov;Y. Masumoto
本工作是对含2个驻留电子或空穴的InAs/GaAs量子点的光学自旋极化的实验研究。将光生电子-空穴对捕获到这样的量子点中，就会产生负的或正的四电子(双电荷激子)。量子点光致发光(PL)的圆偏振记录了自旋极化。发现自旋态在点上完全不同，而在符号电荷上相反。特别是，在GaAs势垒中激发时，负电荷量子点的基态PL极化为负(相对于激发光的偏振)，而正电荷态量子点的基态PL极化为正。随着激发强度的增加，负极化从零上升到饱和水平，而正极化减小。在法拉第几何中，弱磁场使负极化增强，而强场则抑制负极化。正极化总是随着磁场的增加而增大。我们提出了一个定性解释实验结果的理论模型。(2015Wiley-VCH Verlag GmbH&Co.KGaA，Weinheim)
The work is an experimental study of optical spin polarization in InAs/GaAs quantum dots (QDs) with 2 resident electrons or holes. A capture of a photo‐generated electron‐hole pair into such a QD creates a negative or positive tetron (double‐charged exciton). Spin polarization was registered by the circular polarization of the QD photoluminescence (PL). The spin state was found to differ radically in the dots with opposite in sign charge. Particularly, under excitation in a GaAs barrier, the ground state PL polarization is negative (relative to the polarization of an exciting light) in the negatively charged QDs and positive in the positively charged QDs. With increasing excitation intensity, the negative polarization rises from zero up to a saturation level, while the positive polarization decreases. The negative polarization increases in weak magnetic fields applied in Faraday geometry, but strong fields suppress it. The positive polarization always increases as a function of magnetic field. We propose a theoretical model that qualitatively explains the experimental results. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)