Electron Spin Beats in InGaAs/GaAs Quantum Dots

Time resolved picosecond spectroscopy is used for the first time to study optical orientation and spin dynamics of carriers in self-organized In(Ga)As/GaAs quantum dots (QDs) arrays. Optical orientation of carriers created by 1.2 ps light pulses both in the GaAs matrix and wetting layer and captured by QDs is found to last a few hundreds of picosecond. The saturation of electron ground state at high excitation light intensity leads to electron polarization in excited states close to 100 % and to its vanishing in ground state. Electron spin quantum beats in a transverse magnetic field are observed for the first time in semiconductor QDs. We thus determine the quasi-zero-dimensional electron g-factor in In0:5Ga0:5As/GaAs QDs to be: jg?j = 0:27 0:03. Semiconductor structures with quantum dots are currently the subject both of fundamental studies and of practical applications. In the last few years much attention was given to the study of the energy relaxation of carriers in those structures [17]. Taking into account the spin of carriers makes it possible to obtain additional information on the energy relaxation processes and the structure of the electron energy levels. In the present work, time resolve