Fig. 3
Efficient room temperature spin generation enabled by few defects. a Schematic illustration of the defect-driven spin generation via spin-dependent recombination (SDR) under σ+ excitation (the right panel), which shows stronger and co-polarized photoluminescence (PL) than that without the SDR effect under σx excitation (the left panel). The gray horizontal bars represent the defect level. b PL spectra excited by σ+ and σx laser light. c Spectral dependence of the I(σ+)/I(σX) ratio. d Band diagram illustrating the polarized band-to-band transitions involving valence band (VB) heavy-hole (±3/2) and light-hole (±1/2) states. e σ+ and σ− polarized PL spectra under the σ+ excitation. f Spectral dependence of the PL and conduction band (CB) electron spin polarizaion. In converting PPL–Pe, the light depolarization factor arising from the finite solid angle of light detection by the microscope objective with the given numerical aperture (NA) has also been taken into account. Since, the PL emission from GaAs is at least partly contributed from the planar GaAs substrate, Pe in GaAs could be overestimated by a factor up to 1.5
