The stress evolution of Si-doped AlxGa1-xN epilayers with x ranging from 0 to 0.62 was examined using an in situ wafer curvature measurement technique. Transmission electron microscopy was used to assess the effects of Si concentration and composition on defect microstructure. It was found that the density of edge-type threading dislocations (TDs) increased with increasing x, corresponding to the evolution of higher magnitudes of tensile stress, attributed to TD inclination. The results are discussed in the context of proposed inclination mechanisms that feature jog formation as the process leading to TD inclination. (C) 2009 Elsevier B.V. All rights reserved.