Effect of Si doping on the strain and defect structure of GaN thin films

The amount of strain was measured in GaN films using X-ray diffraction, Ram an, and curvature techniques as a function of film thickness and the Si dop ing concentration. It was found that for a doping concentration of 2 x 10(1 9), the threshold thickness for crack formation was about 2.5 mu m. Transmi ssion electron microscopy observations showed that cracking proceeds withou t plastic deformation (i.e., no dislocation motion), and occurs catastrophi cally along the low-energy {1 (1) under bar 0 0} cleavage plane of GaN. (C) 1999 Elsevier Science B.V. All rights reserved.