Prolonged spin relaxation time in Zn-doped GaAs/GaAsP strain-compensated superlattice

A GaAs/GaAsP strain-compensated superlattice (SL) is a highly promising spin-polarized electron source. To realize higher quantum efficiency, it is necessary to consider spin relaxation mechanisms. We have investigated the electron spin relaxation time in a Zn-doped GaAs/GaAsP strain-compensated SL by time-resolved spin-dependent pump and probe reflection measurements. The long spin relaxation time of 104 ps was observed at room temperature (RT), which is about three times longer than that of conventional undoped GaAs multiple quantum wells. Even when the excitation power increases from 30 to 110 mW, the change in the spin relaxation time at RT was small. This relationship implies that the intensity of the electron beam can be increased without affecting the spin relaxation time. These results indicate that a Zn-doped GaAs/GaAsP strain-compensated SL has the great advantage for use as a spin-polarized electron source.