The characteristics of confined epitaxial growth are investigated with the goal of determining the contributing effects of mask attributes (spacing, feature size) and growth conditions (V/III ratio, pressure, temperature) on the efficiency of the approach for dislocation density reduction of GaN. In addition to standard (secondary electron and atomic force) microscopy, electron channeling contrast imaging (ECCI) is employed to identify extended defects over large (tens of microns) areas. Using this method, it is illustrated that by confining the epitaxial growth, high quality GaN can be grown with dislocation densities approaching zero. (C) 2010 Elsevier B.V. All rights reserved.