Spin orientation of excitons, trions and tetraons in charge tunable InP quantum dots

Abstract

In the longitudinal magnetic field, photoluminescence (PL) polarization in InP quantum dots (QDs) dramatically changed depending on the number of doped electrons. Under linearly polarized excitation, PL polarizes resonantly at two magnetic fields where bright and dark excitons anticross each other in neutral QDs. On the other hand, PL polarization monotonously increases with the increase of longitudinal magnetic field in one‐ and two‐electron doped QDs, where thermal spin orientation of a photoexcited hole determines the PL polarization of a trion and a tetraon. At low temperatures, however, the electron‐hole exchange interaction reduces the thermal spin orientation of holes. In two‐electron doped QDs, the anisotropic electron‐hole exchange interaction gives small structure in the magnetic‐field‐dependent circular polarization at the low field region. Time‐resolved circular polarization clearly shows the dynamical spin polarization process in charged QDs in the longitudinal magnetic field. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Spin orientation in charge-tunable InP quantum dots

“…The ratio of existing probabilities of * and + holes, n * and n + , is written by n * /n The correction factor of t/(t+t s ) was evaluated by the temporal changes of PL and PL circular polarization [7]. The evaluated P c increases in proportion to the longitudinal magnetic field consistently with the experimental result, but is still twice larger than the experimental result at 5 K shown in Fig.…”