Observation of interdot tunneling process of spin-polarized electrons

We have directly observed the spin-polarized electron tunneling process between double quantum dots (QDs) using spin-dependent time-resolved photoluminescence measurements. The spin relaxation times in isolated In0.9Al0.1As Stranski–Krastanow (SK)-mode QDs and InAs SK-mode QDs were measured as 1.3 and View the MathML source, respectively. The fact that these times are longer than those of quantum wells indicates that the spin relaxation rate is suppressed in QDs by the increased zero dimensionality. The measurement of tunneling between double QDs which consist of In0.9Al0.1As QDs and InAs QDs indicates that the spin relaxation time is not affected by the tunneling process. The spin-polarized carriers were found to tunnel from one dot to another dot while retaining spin polarization.