The mechanical strength of bulk monocrystalline wurtzite phase, grown using the hydride vapor-phase epitaxy technique, was investigated at high temperatures by means of compressive deformation. The yield stress at 900 to 1000C was about 100 to 200MPa. This was similar to that of 6H-SiC, and much higher than that of Si or GaAs. On the basis of the temperature dependence of the yield stress, the activation energy for dislocation motion was estimated to be 2 to 2.7eV.

Yield Strength and Dislocation Mobility in Plastically Deformed Bulk Single-Crystal GaN. I.Yonenaga, K.Motoki: Journal of Applied Physics, 2001, 90[12], 6539-41