Spin-photonic semiconductor devices based on (110) quantum wells: Spin-VCSELs and spin-switches

In this paper, recent progress in spin-photonic semiconductor devices based on (110) quantum wells (QWs) is reviewed, which include spin-vertical-cavity surface-emitting lasers (spin-VCSELs) and spin-switches. We fabricated a (110)-oriented VCSEL with GaAs/AlGaAs multiple QWs (MQWs), and demonstrated circularly polarized lasing with a high degree of circular polarization of 0.96 at room temperature that originated from a long electron spin relaxation time of 0.7 ns. We also investigated carrier lifetime and electron spin relaxation time in (110)-oriented GaAs/AlGaAs MQW micro-posts and found that the long electron spin relaxation time is preserved even when the sidewall boundaries with fast surface recombination are introduced and the carrier lifetime is drastically shortened. Moreover, we fabricated a (110)-oriented p-i-n structure with a GaAs/AlGaAs MQW and demonstrated a tenfold modulation of the electron spin relaxation time from 4.0 ns to 0.3 ns in the QWs by applying an external electric field at room temperature.