Edge Absorption of thin Films b–Ga₂O₃

Abstract

Fundamental absorption edge of b–Ga₂O₃ thin films, obtained by radio-frequency ion-plasmous sputtering, was investigated, using the method of optical spectroscopy. It was ascertained that the optical band gap Eg increases from 4.60 to 4.65 eV after the heat treatment films in argon atmosphere and to 5.20 eV after the reduction of annealed films in a hydrogen atmosphere. Consolidated effective mass of free charge carriers in b–Ga₂O₃ films after annealing and after reduction in hydrogen was estimated. It was found that the concentration of charge carriers after heat treatment in argon atmosphere is 7.30´10¹⁷ cm^–3 and after reduction in hydrogen, is 2.62´10¹⁹ cm^–3 , which is typical for degenerated semiconductors. It was shown that the shift of fundamental absorption edge in thin films b–Ga₂O₃ after reduction in hydrogen is caused by Burstein-Moss effect.Keywords: gallium oxide, thin films, fundamental absorption edge.