Quantum-well heterointerfaces of AlGaAs on GaAs(1 0 0), (1 1 1)A. and (3 1 1)A were fabricated by molecular beam epitaxy (MBE) growth with interruption of Ga supply and then observed by photoluminescence (PL) measurements. The PL measurements showed that the interruption caused these heterointerfaces to roughen, and this roughening, was proportional to the resulting increase in the quantum well widths. (C) 2002 Elsevier Science B.V. All rights reserved.