We have studied the magneto-photo luminescence (PL) of triply stacked layers of self-assembled InP quantum dots, For a small separation of the uppermost dot in (he triple stack from the other two closely stacked layers, only one PL peak is observed, whereas for a large separation two PL peaks are present: a broad low-energy and a narrow high-energy peak. We propose a model in which the low-energy peak is associated with the uppermost dot where alignment faults result in enhanced size fluctuations, broadening the line, The narrow high-energy peak originates from charges located in the double stack. In the large separation regime, an increased broadening of the PL line-width indicates that the size fluctuations are augmented as the layer separation is increased from 15 to 30 nm. (C) 2002 Elsevier Science B.V. All rights reserved.