We present the control of the emission wavelength of InAs quantum dots in a GaInAsP matrix grown on InP(311)B substrates by g-as source molecular beam epitaxy. By growing the capping layer in two steps, the control of the dot height and thus of the emission wavelength is achieved. The dot height is tuned using As/P exchange during a growth interrupt. We have studied the changes induced by the nature of the overpressure (As, P, As and P) during the growth interrupt. Photoluminescence spectra at room temperature show the effects of the different growth parameters on the peak energy and width. (C) 2004 Elsevier B.V. All rights reserved.