The growth of GaN-based transistor structures on silicon substrates requires strain engineering to compensate tensile thermal stress upon cooling and prevent crack formation. For high compressive stress during growth, required for thick GaN layers, plastic substrate deformation can occur. Several methods as in-situ curvature, and ex-situ XRD as well as electrical device measurements demonstrate the impact of different substrate thicknesses and substrate types on anisotropic bow, material data and device properties. (C) 2012 Elsevier B.V. All rights reserved.