Correlation between electron spin relaxation time and hetero-interface roughness in (1 1 0)-oriented GaAs/AlGaAs multiple-quantum wells

The correlation between the electron spin relaxation time τs and the hetero-interface roughness in (1 1 0)-oriented GaAs/AlGaAs multiple-quantum wells (MQWs) was investigated using growth interruption during molecular beam epitaxy growth. τs was characterized using polarization- and time-resolved PL measurements, and the hetero-interface roughness was evaluated by the full-width-at-half-maximum of the PL spectra at 4 K. It was found that τs in the MQWs with smooth interfaces became longer and the temperature dependence of τs changed from τs∼T0.6–T0.9 when the interface roughness was reduced using growth interruption. These results indicate that the structure inversion asymmetry term of the D’yakonov-Perel’ mechanism was suppressed in the MQWs with smooth hetero-interfaces.