Effect of temperature on the nanoindentation behavior of single crystal GaN by molecular dynamics simulations

Comprehending the nano-deformation mechanisms of GaN under the joint influence of temperature and loads is significant for the production and reliability service of high-quality GaN-based devices. Nanoindentation molecular dynamics simulations are conducted on the c-plane of wurtzite GaN single crystal samples within the temperature range of 10K–1200K. The results indicate that the mechanical properties of GaN exhibit favorable temperature stability. The pop-in events observed in GaN nanoindentation are caused by dislocation nucleation beneath the surface. The dynamics of dislocation motion during the GaN nanoindentation process are explained. An analysis of the interactions between dislocations revealed dislocation entanglement and atomic compression in GaN during multi-point loading. Two phase transformations are recognized in GaN: the wurtzite structure changes to the h-MgO structure in the elastic deformation and transformations to the zinc blende structure during plastic deformation. It is found that there is a correlation between 1/3<10 $\bar{1}$ 0> dislocations and the zinc blende phase transformation. The study revealed that higher temperatures slightly enhance the plastic deformation of GaN while promoting phase transformation to zinc blende. This research analyzed the deformation and damage mechanisms in GaN crystals during mechanical loading at various temperatures, offering significant theoretical foundations for the production and fabrication of GaN-based devices.