Defect evolution induced by low-dose neutron irradiation and elastoplastic deformation mechanism of indium-doped GaN materials

Abstract

The low-dose neutron irradiation defect evolution and nanoindentation response of indium (In)-doped gallium nitride (GaN) materials are investigated in this work, which is of great significance for improving the reliability and safety of nitride semiconductors in neutron irradiation environments, as well as for clarifying their mechanical properties. A numerical simulation approach based on molecular dynamics (MD) is utilized to construct wurtzite GaN models comprising Indium doping concentrations up to 2%. Nanoindentation simulations are performed to analyze the elastoplastic deformation mechanisms of the c-plane and m-plane In-doped GaN materials. The low-dose neutron irradiation process of In-doped GaN is further simulated, and its structural changes and defects evolution are analyzed. The indentation hardness of the c-plane GaN decreases and its Young’s modulus increases as the doping concentration increases. Increases in both the indentation hardness and Young’s modulus are seen for the m-plane GaN with the increasing doping concentration. Moreover, the doping of indium suppresses the plastic deformation both in the c-plane and m-plane GaNs. Two types of prismatic loops formation mechanisms are unraveled, i.e. the “nested shear loops pinch-off” mechanism in the m-plane perfect GaN, and the “lasso-shape shear loop pinch-off” mechanism in the m-plane In-doped GaN. When subject to low-dose neutron irradiation, In-doped GaN materials exhibit higher resistance to the generation of irradiation defects. As the doping concentration increases, the amounts of phase transformation, Frenkel pairs, and amorphization decrease.