Yield strength and dislocation mobility in plastically deformed bulk single-crystal GaN

The mechanical strength of bulk single-crystal wurtzite-GaN grown by the hydride vapor phase epitaxy technique is investigated at elevated temperatures by means of compressive deformation. The yield stress of GaN in the temperature range 900-1000°C is around 100-200MPa, i.e., similar to that of 6H-SiC and much higher than those of Si and GaAs. From the temperature dependence of the yield stress an activation energy for dislocation motion in the GaN is estimated to be 2-2.7eV.