Nanooptics and photonics 

Peculiarities of carrier relaxation in hybrid quantum dot-wells structures 

Z. Ya. Zhuchenko1, V. Laurindo Jr.2, E. R. Cardozo de Oliveira2, B. Alén3, G.G. Tarasov1, G. E. Marques2, M.D. Teodoro2, M. E. Ware5, E. Marega4, Yu. I. Mazur5, and G. J. Salamo5

1 V.E. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences, pr, Nauki 45, Kiev-03028, Ukraine
2Departamento de Física, Universidade Federal de São Carlos, 13565-905, São Carlos, São Paulo, Brazil
3Instituto de Micro y Nanotecnología, IMN-CNM, CSIC (CEI UAM+CSIC)Isaac Newton, 8, E-28760, Tres Cantos, 28760, Madrid, Spain
4 Instituto de Física de São Carlos, Universidade de São Paulo, 13.566-590, São Carlos, São Paulo, Brazil
5 Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR 72701, USA
E-mail: zhuchenko@isp.kiev.ua

Quantum dot - quantum well heterostructures represent a class of hybrid structures whose photoluminescence wavelength depends on the dot sizes, well width, and the dot-well barrier deﬁning the strength of dot-well coupling. Variation of these parameters provides wide tuneability in the engineering of these systems for opto-electronic applications including high-performance lasers, quantum information processors, or single electron transistors. In order to use in high-speed tunnel injection QD lasers, the injected carriers are ﬁrst collected by the QW, then tunnel into the QDs with subsequent relaxation to the ground state for laser action. However, application of a magnetic field to such structures allows for additional valuable information to be collected, because it introduces a strong but predictable change to the electronic structure. At high magnetic fields, where the cyclotron energy is larger than both the lateral confinement energy and the exciton binding energy, the magnetic confinement dominates and a Landau-level-like structure is expected to develop. The magnetic field also removes the spin degeneracy giving rise to qualitatively different magnetic field dependences of the emission from the ground and excited states. It is especially important in the case of dot-well structures where excited QD states are brought into resonance with the QW ground or excited exciton states. Peculiarities of carrier relaxation in such structures are investigated here under magnetic field up to 9 Tesla and demonstrate the universality of semi classical WKB approximation.