Deposition of indium oxide from metallic indium with post-growth oxidation: electrical conduction control and persistent photoconductivity

ABSTRACT Indium (In) thin films are resistively evaporated with distinct thickness on silica and soda-line glass substrates, which receives distinct sort of cleaning. These cleaning procedures are compared concerning the film roughness, which is higher for In films deposited on glass substrate compared to silica, regardless of the cleaning method used. In films are oxidized to indium oxide (In 2 O 3 ) at different temperatures. The resulting In 2 O 3 films present larger crystallite size within films deposited on glass, cleaned with an ozone treatment, which may be related to the higher localized accumulation of material on the glass substrates, probably related to the higher roughness, which drives the growth kinetics. Films 100 nm thick showed better formation of a crystalline structure of indium oxide, when thermally annealed at 400 °C. In 2 O 3 obtained from oxidation of resistively evaporated In films present semiconductor behavior and n-type conduction. The electrical conductivity is discussed considering ionization of oxygen vacancies and electron scattering at grain boundary, and two main intrabandgap levels are found at 15.6 and 50.6 meV. The phenomenon of persistent photoconductivity is observed at low temperature and surprisingly close to room temperature which reveals potential for application in memory devices.