  We report on the influence of disorder on an exciton-polariton condensate in
a ZnO based bulk planar microcavity and compare experimental results with a
theoretical model for a non-equilibrium condensate. Experimentally, we detect
intensity fluctuations within the far-field emission pattern even at high
condensate densities which indicates a significant impact of disorder. We show
that these effects rely on the driven dissipative nature of the condensate and
argue that they can be accounted for by spatial phase inhomogeneities induced
by disorder, which occur even for increasing condensate densities realized in
the regime of high excitation power. Thus, non-equilibrium effects strongly
suppress the stabilization of the condensate against disorder, contrarily to
what is expected for equilibrium condensates in the high density limit.
Numerical simulations based on our theoretical model reproduce the experimental
data.
