טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentAlon Gabbay
SubjectThe Effect of Magnetic Field on Charged Polaritons in
Microcavities
DepartmentDepartment of Physics
Supervisor Professor Emeritus Cohen Elisha


Abstract

   Semiconductor microcavities (MC) are structures consisting of a cavity layer cladded by a distributed Bragg reflector on each side. A quantum well (QW) is embedded within the MC. The spatially confined photon interacts strongly with the QW excitons at resonance.  In the strong coupling regime, the system eigenstates are admixed exciton-photon states (cavity polaritons) that are split by the Rabi splitting. We report the results of reflection and photoluminescence (PL) spectroscopy and the effect of magnetic field on cavity polaritons in a structure containing a two dimensional electron gas (2DEG). A comparison is reported between a bare modulation doped quantum well (MDQW), and one that embedded in a microcavity.

   The main observations of this study are: (a) exciton-like transitions appear in the photoluminescence

of the MDQW at magnetic fields where the filling factor, ν, is smaller than 1. Stronger exciton-like transitions appear as the density of the electron gas is decreased. (b) The spin splitting of the electron gas in the MDQW is dominated at low magnetic fields by a mechanism other than the zeeman mechanism and shows a dependence on the electron density. (c) The confined photon causes an admixture of the spin states of the exciton-like transitions associated with the 2DEG. (d) The spin splitting of the polaritons in the microcavity exhibit a totally different behavior than that observed in the bare quantum well. (e) The reflection spectra of the MDQW/MC reveals polaritonic energy levels, some of which are not accounted for by the picture of interacting Landau levels with the cavity mode.