It is shown experimentally that the thickness and composition of Ga1-xAlxSb layers grown by liquid phase epitaxy on Gasb substrates depend on the conductivity type of the substrates. To avoid experimental uncertainties that naturally happen from an experiment to another one, such as changes in the exact liquid composition, growth temperature, temperature gradients, etc., the Ga1-xAlxSb layers have been grown simultaneously from the same liquid solution on N and P type GaSb substrates. The X-ray rocking curves show that for every couple of layers, grown on N and P type substrates, there is a consistent difference between their thickness and composition. The thickness difference has also been verified by optical microscopy. A likely explanation of this effect is a change in surface energy of the substrate induced by the surface electric field normally present in semiconductors. (C) 2010 Elsevier B.V. All rights reserved.