Growth condition dependence of photoluminescence polarization in (100) GaAs/AlGaAs quantum wells at room temperature

We conducted systematic measurements on the carrier lifetime (tau(c)), spin relaxation time (tau(s)), and circular polarization of photoluminescence (P-circ) in (100) GaAs/AlGaAs multiple quantum wells grown by molecular beam epitaxy (MBE). The tau(c) values are strongly affected by MBE growth conditions (0.4-9 ns), whereas the ss are almost constant at about 0.13 ns. The result suggests that spin detection efficiency [tau(s)/(tau(c)+tau(s))], which is expected to be proportional to a steady-state P-circ, is largely dependent on growth condition. We confirmed that the P-circ has similar dependence on growth condition to those of tau(s)/(tau(c)+tau(s)) values. The study thus indicates that choosing the appropriate growth condition of the QW is indispensable for obtaining a high P-circ from a spin-polarized light-emitting diode (spin-LED). (C) 2015 AIP Publishing LLC.