Analysis of doping induced wafer bow during GaN:Si growth on sapphire

Abstract

In-situ curvature measurements were employed to quantify stress generation during metalorganic vapor phase epitaxy growth of Si-doped GaN sandwiched between undoped GaN layers. It is shown that the creation of tensile stress in Si-doped GaN is closely linked to the density of threading dislocations in the material. Accompanying characterization by in-situ reflectance measurements and TEM analysis supports the model that the doping induced stress formation is caused by a surface-mediated dislocation climb process. In addition, curvature measurements reveal an unusual partial relaxation in GaN:nid grown atop of highly doped GaN:Si layers. This relaxation is assigned to a notable dislocation annihilation at the upper GaN:Si+/GaN:nid interface found by TEM probably due to the formation of a thin SiNx masking layer.