Size dependence of electron spin dephasing in InGaAs quantum dots

• Published in: Applied physics letters Vol. 106; no. 9; p. 093109
• Main Authors: Huang, Y. Q., Puttisong, Y., Buyanova, I. A., Yang, X. J., Subagyo, A., Sueoka, K., Murayama, A., Chen, W. M.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 02-03-2015
• Subjects: Applied physics; CONFINEMENT; Dependence; Electron spin; ELECTRONS; EXCITATION; FLUCTUATIONS; GALLIUM ARSENIDES; Hyperfine structure; INDIUM ARSENIDES; Indium gallium arsenides; INTERFACES; NANOSCIENCE AND NANOTECHNOLOGY; QUANTUM DOTS; RECOMBINATION; Self-assembly; SPIN; Trions; Variation
• ISSN: 0003-6951; 1077-3118; 1077-3118
• DOI: 10.1063/1.4914084

We investigate ensemble electron spin dephasing in self-assembled InGaAs/GaAs quantum dots (QDs) of different lateral sizes by employing optical Hanle measurements. Using low excitation power, we are able to obtain a spin dephasing time T2* (in the order of ns) of the resident electron after recombination of negative trions in the QDs. We show that T2* is determined by the hyperfine field arising from the frozen fluctuation of nuclear spins, which scales with the size of QDs following the Merkulov-Efros-Rosen model. This scaling no longer holds in large QDs, most likely due to a breakdown in the lateral electron confinement.