No spin polarization of carriers in InGaN

We report the spin polarization of carriers photoexcited in bulk InGaN by circularly polarized femtosecond optical pulses. No spin polarization is observed in the picosecond time region using spin-dependent pump and probe absorption measurements with a time resolution of 0.35 ps. This is in contrast to the existence of spin polarization in GaAs quantum wells or in InGaAs quantum wells which have a spin relaxation time in the picosecond time region. The unique band structure of InGaN, which has weak spin–orbit interaction, and an in-plane potential fluctuation due to the compositional inhomogeneity of In explains the lack of spin polarization.