Spontaneous nonground state polariton condensation in pillar microcavities

We observe spontaneously driven nonground state polariton condensation in GaAs pillar microcavities under nonresonant optical excitation. We identify a regime where the interplay of exciton-exciton and pair polariton scattering can lead to mode switching from nonground state to ground state polariton condensation. A simple kinematic model satisfactorily describes the observed mode switching as each of the above scattering mechanisms becomes prevalent at different carrier densities.