Browsing by Subject "damage"

Ga2O3 has been found to exhibit excellent radiation hardness properties, making it an ideal candidate for use in a variety of applications that involve exposure to ionizing radiation, such as in space exploration, nuclear power generation, and medical imaging. Understanding the behaviour of Ga2O3 under irradiation is therefore crucial for optimizing its performance in these applications and ensuring their safe and efficient operation. There are five commonly identified polymorphs of Ga2O3 , namely, β, α, γ, δ and structures, among these phases, β-Ga2O3 is the most stable crystal structure and has attracted majority of the recent attention. In this thesis, we used molecular dynamic simulations with the newly developed machine learned Gaussian approximation potentials to investigate the radiation damage in β-Ga2O3 . We inspected the gradual structural change in β-Ga2O3 lattice with increase doses of Frenkel pairs implantations. The results revealed that O-Frenkel pairs have a strong tendency to recombine and return to their original sublattice sites. When Ga- and O-Frenkel pairs are implanted to the same cell, the crystal structure was damaged and converted to an amorphous phase at low doses. However, the accumulation of pure Ga-Frenkel pairs in the simulation cells might induce a transition of β to γ-Ga, while O sublattice remains FCC crystal structure, which theoretically demonstrated the recent experiments finding that β- Ga2O3 transfers to the γ phase following ion implantation. To gain a better understanding of the natural behaviour of β-Ga2O3 under irradiation, we utilized collision cascade simulations. The results revealed that O sublattice in the β-Ga2O3 lattice is robust and less susceptible to damage, despite O atoms having higher mobility. The collision and recrystallization process resulted in a greater accumulation of Ga defects than O defects, regardless of PKA atom type. These further revealed that displaced Ga ion hard to recombine to β- Ga lattice, while the FCC stacking of the O sublattice has very strong tendency to recovery. Our theoretical models on the radiation damage of β-Ga2O3 provide insight into the mechanisms underlying defect generation and recovery during experiment ion implantation, which has significant implications for improving Ga2O3 radiation tolerance, as well as optimizing its electronic and optical properties.