Edge Absorption of (Y_0.06Ga_0.94)₂O₃ Thin Films

Abstract

Fundamental absorption edge of (Y0.06Ga0.94)2O3 thin films, obtained by radio-frequency ion-plasmous sputtering, was investigated using the method of optical spectroscopy. It was established that these films are formed in the monoclinic structure of β-Ga2O3. The optical band gap of these films is greater than β-Ga2O3 films and is 4.66 eB for films annealed in oxygen atmosphere, 4.77 eV for the films annealed in argon atmosphere and 4.87 eV for the films, restored in a hydrogen atmosphere. Consolidated effective mass of free charge carriers in (Y0.06Ga0.94)2O3 films after annealing and after reconstitution in hydrogen was estimated. It was found that the concentration of charge carriers after annealing in oxygen atmosphere is 1.32×1018 cm-3, after annealing in argon atmosphere - 3.41×1018 cm-3 and after reconstitution in hydrogen is 5.20×1018 cm-3, which is typical for degenerated semiconductors. It was shown that the shift of fundamental absorption edge in (Y0.06Ga0.94)2O3 thin films is caused by Burstein-Moss effect. Key words: gallium and yttrium oxide, thin films, fundamental absorption edge.