Luminescence Studies of Er:Ga₂O₃ Films: Effect of Growth and Annealing Temperatures and Oxygen Pressures

Er³⁺ doped Ga₂O₃ is a very promising material for data storage, full color display and white light emitting devices due to its sharp green emission, large direct bandgap, and thermal and chemical stability. In this paper, we report the growth of Er³⁺ doped Ga₂O₃ films on (111) silicon substrates by using the method of pulsed laser deposition with a series of varied growth conditions that include substrate temperature and O₂ pressure. The results of cathodoluminescence measurements reveal that the Er³⁺ doped Ga₂O₃ films, grown at the substrate temperature of 450 °C and O₂ pressure of 0.1 mbar, exhibit a strong green emission. The Er³⁺ doped Ga₂O₃ films were thermally treated at temperatures ranging from 800 to 1000 °C, and the X-ray diffraction analysis indicates that annealing temperature of 900 °C leads to the best crystal quality. Moreover, we have also found that the cathodoluminescence of Er³⁺ doped Ga₂O₃ films can be significantly increased by the thermal treatment at 900 °C. To explain the cathodoluminescence mechanism of Er³⁺ doped Ga₂O₃ film, the band structure and electronic transitions in Er³⁺ doped Ga₂O₃ material have been discussed and clarified in detail. This work presents a pathway towards the applications of the Er³⁺ doped Ga₂O₃ material in optoelectronic devices.