Picosecond electron-spin relaxation in GaAs/AlGaAs quantum wells and InGaAs/InP quantum wells

The spin-relaxation process of electrons at room temperature is investigated for GaAs/AlGaAs multiple-quantum wells (MQWs) and InGaAs/InP MQWs. The spin-relaxation times are measured for various well thicknesses using time-resolved spin-dependent pump and probe absorption measurements. The spin-relaxation time, tau(s), for GaAs MQWs was found to depend on the electron confinement energy, E-1e, according to tau(s) proportional to E-le(-2.2), demonstrating that the main spin-relaxation mechanism at room temperature is the D'yakonov-Perel' process. The measured tau(s) of InGaAs MQWs vary depending on the quantum confinement energy, E-le, according to tau(s) proportional to E-le(-1.0). tau(s) for QWs by the Elliott-Yafet process is calculated and shown to vary according to tau(s) proportional to E-le(-1). The spin-relaxation mechanism and possible applications using this fast spin-relaxation process are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.