Modulating the blue and green luminescence in the β-Ga₂O₃ films

In this work, the β-Ga₂O₃ films were fabricated by radio frequency magnetron sputtering on the c-plane sapphire substrates with the (2¯01) preferred orientation. The blue and green luminescence of β-Ga₂O₃ films have been systemically studied. By changing the concentration of intrinsic vacancies in β-Ga₂O₃ films through increasing oxygen flow rate during sputtering, the intensity of blue and green luminescence were modulated. The maximum value of the intensity ratio for green luminescence to blue luminescence reached to 433.37% when the oxygen flow rate arrived at 6 sccm. Combining experiments with density functional theory calculations, this work had proved the green luminescence in β-Ga₂O₃ mainly originated from the isolated gallium vacancies. While the isolated oxygen vacancies could not play the important roles in the blue emission independently. The blue luminescence most likely resulted from complex defects such as (V_OI+V_GaI)⁻ or the optical transitions between V_O and (V_O, V_Ga). Thus, changing the concentration of intrinsic vacancies is highly effective for β-Ga₂O₃ to modulate the intensity of green luminescence and blue luminescence.