E!ect of Si doping on the strain and defect structure of GaN thin "lms

The amount of strain was measured in GaN "lms using X-ray di!raction, Raman, and curvature techniques as a function of "lm thickness and the Si doping concentration. It was found that for a doping concentration of 2]1019, the threshold thickness for crack formation was about 2.5 lm. Transmission electron microscopy observations showed that cracking proceeds without plastic deformation (i.e., no dislocation motion), and occurs catastrophically along the low-energy M1 1 1 0 0N cleavage plane of GaN. ( 1999 Elsevier Science B.V. All rights reserved.