In situ measurement of stress generation arising from dislocation inclination in Al_xGa_1-xN:Si thin films

The effect of Si-doping on the stress and microstructure of Al _xGa_1-xN (x≈0.39-0.45) films grown by metalorganic chemical vapor deposition on SiC substrates was investigated. In situ measurements revealed a compressive-to-tensile transition of the stress state at the film surface upon the addition of SiH4 during growth, which correlated with a change in the angle of inclination of threading dislocations in the film. The magnitude of the in situ measured stress gradient was comparable to that predicted by the dislocation effective climb model, suggesting that dislocation inclination is the dominant mechanism responsible for tensile stress generation in the films.