Three techniques have been combined to correlate interface morphology and optical properties of single AlAs‐GaAs quantum wells grown by molecular beam epitaxy (MBE) with and without growth interruption at the inverted (GaAs on AlAs) interface. Surface recovery and interface formation were monitoredinsituby reflection high energy electron diffraction, optical properties were assessed by photoluminescence excitation (PLE) spectroscopy and the results compared with a Monte Carlo simulation of MBE growth, extended to evaluate PLE linewidths. Criteria for linewidth reduction have been established and interface morphology described.