  We study the photoluminescence from a near-surface quantum well in the regime
of ambipolar tunneling to the surface states. Under steady-state excitation an
electric field develops self-consistently due to the condition of equal
tunneling currents for electrons and holes. The field induces a Stark shift of
the photoluminescence signal which compares well with experimental data from
near-surface GaAs/AlGaAs single quantum wells.
