Stress evolution during metalorganic chemical vapor deposition of GaN

The evolution of stress in gallium nitride films on sapphire has been measu red in real time during metalorganic chemical vapor deposition. In spite of the 16% compressive lattice mismatch of GaN to sapphire, we find that GaN consistently grows in tension at 1050 degrees C. Furthermore, in situ stres s monitoring indicates that there is no measurable relaxation of the tensil e growth stress during annealing or thermal cycling. (C) 1999 American Inst itute of Physics. [S0003-6951(99)04603-3].