We have investigated the electron spin relaxation time of a (110)-oriented GaAs/AlGaAs superlattice (SL) with tunnel-coupled quantum wells at room temperature. As the tunnel coupling between quantum wells increased, the spin relaxation time decreased. Even when the strength of tunnel coupling was as large as 25 meV, the spin relaxation time was 0.7 ns, about seven times longer than that of bulk GaAs which has been used as a conventional spin transport layer. This finding indicates that (110)-oriented SL structures are one of the potential candidates for spin transport in both in-plane and out-of-plane directions in semiconductor-based spintronic devices.

We have systematically investigated the structural properties, carrier lifetimes, namely, photoluminescence (PL) lifetimes (τPL), and electron spin relaxation times (τs) in (110) GaAs/AlGaAs multiple quantum wells (MQWs) by using time-resolved PL measurements. The MQWs were grown by molecular beam epitaxy within a wide range of the growth temperature Tg (430–600 °C) and a high V/III flux ratio using As2. At 530 °C < Tg < 580 °C, we found that the quality of the heterointerfaces is significantly improved, resulting in τPL~40 ns at RT, one order of magnitude longer than those reported so far. Long τs (~6 ns) is also observed at RT.

No abstract