The metastable nature of wurtzite InGaN alloys is exhibited in the numerous reports linking compositional fluctuations to electron microscopy and luminescence measurements. The electronic effects of these fluctuations can be simplified by a spatial variation of the bulk band gap. We have examined both the electrostatic potential and relative atomic density of In 0.13Ga0.87N 10nm-wide quantum wells containing In-compositional fluctuations and electrostatic potential fluctuations, using electron holography (EH) and electron tomography (ET). EH has shown the potential fluctuations are localized near to the substrate, are 2-3nm in size, and have negatively charged cores. Our ET 3D density maps of the In distribution reveal the existence of quantum dot like regions (QDs) of high In% also localized to within 3nm of the substrate, 3-5nm in width, and spaced ∼8nm apart. © 2005 American Institute of Physics.