Linear morphological features which are readily revealed using Nomarski interference contrast microscopy have been observed on the surfaces of GaxAl1−xAs epitaxial layers grown by liquid phase epitaxy LPE on GaAs substrates at 950 °C. These features are introduced along one <110≳ direction in the (001) growth surface only. Annealing at the growth temperature produces a similar set of features in the perpendicular <110≳ direction. Photoluminescence topographs reveal dark lines in the substrates that are directed parallel to the sets of surface features in both annealed and unannealed crystals.