Seminarium Fizyki Ciała Stałego

-Ga2O3 as a wide bandgap semiconductor (4.8eV) with unique properties, is a potential candidate for various optoelectronic applications, such as high-power LED, high-end displays, car sensors, and UV photodetectors. High radiation resistance paved the way for it to be used as a material working in extremely radiative and harsh environments. Such conditions induce damage in the crystal lattice, which eventually affects the device’s efficiency and lifetime. In addition, optical tuning of -Ga2O3 for example, by doping with rare-earth (RE) ions is important for its prospective applications. This material has especially proven itself as a suitable host for RE ions. Ion implantation is an efficient technique for doping material due to its many advantages, such as controlled dopant concentration and depth location. However, it creates lattice damage and can cause optical inactivation of RE dopant; therefore, annealing is necessary. To address this problem, we implanted -Ga2O3 single crystals with different RE ions and annealed them in various conditions. Based on Channeling Rutherford Backscattering Spectrometry (RBS/c) accompanied by McChasy computer simulations we analyzed defects evolution after implantation and we were able to determine for the first time the defect accumulation curve for this material. Two different damage regions were revealed, indicating the complexity of defects after irradiation, and their different reaction to rapid thermal annealing (RTA). We observed that defect accumulation process in this material occurs in an unusual way and, for some fluences, it results in appearance of a new crystallographic phase, -Ga2O3, that is formed about 60 nm below the crystal surface as confirmed by TEM images. We also observed that the lattice structure recovery level after annealing decreases with increasing ion fluence, and above a particular fluence (< 0.5 dpa), complete RTA resistance was noticed. Further, for selected fluence, various annealing conditions were tested for comprehensive studies of recovery and the optical response of RE to structural changes. Acknowledgments The work was performed within the co-financed international project of the MNiSW (5177/HZDR/2021/0) and Helmholtz Zentrum Dresden Rossendorf project (20002208-ST), supported also by the NCN project UMO-022/45/B/ST5/02810.