In a recent paper, we measured the hole diffusion length in a single quantum well (SQW) by a novel method using SEM-cathodoluminescence, assuming that the carriers diffuse only in the SQW. This assumption needs to be checked. Therefore, we present here a model for the carrier transport in the SQW and in the bulk barrier to deduce the lateral hole distribution in both layers. The main lateral transport is shown to be carried by the holes in the QW (2D diffusion) due to their confinement in the well.