Edge Absorption of thin Films –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.

Influence of the Obtaining Conditions on the Photoconductivity of Thin β-Ga2O3 Films

“…Taking into account that the band gap of thin -Ga 2 O 3 films annealed, for example, in oxygen atmosphere is equal to 4.60 eV (270 nm) [21], the excitation of the luminescence and photoconductivity bands occurs in the region of the band-to-band transitions with the formation of free charge carriers in conduction band. This is the socalled own optical generation and, accordingly, intrinsic photoconductivity.…”

“…This is revealed out in the spectral shift of the photoconductivity excitation band maximum from 245 nm (5.05 eV) for -Ga 2 O 3 films, which were annealed in oxygen atmosphere to 270 nm (4.60 eV) for unannealed of -Ga 2 O 3 films. Taking into account that, according to [21], the optical band gap E g of thin -Ga 2 O 3 films increases from 4.60 eV (270 nm) for films annealed in oxygen atmosphere, up to 4.65 eV (267 nm) for films annealed in argon atmosphere and to 5.20 eV (240 nm) after the reduction of annealed films in hydrogen atmosphere, this most likely results in the spectral shift of the photoconductivity maximum of thin -Ga 2 O 3 films after annealing in argon atmosphere and reduction in hydrogen atmosphere in the region of 235 nm (5.27 eV).…”

The Influence of Europium Impurity on the Recombination Luminescence in Y2O3

“…The doping of the material by Eu 3+ ions leads to the appearance of the activator centers luminescence [10]. In this paper we have done the comparative study and have analyzed the spectra of X-ray luminescence (XRL) and the curves of thermostimulated luminescence (TSL) of Y 2 O 3 and Y 2 O 3 :Eu 3+ ceramics at the X-ray excitation in the 85-295 K range for the obtaining of additional information about the influence of Eu 3+ ions on the features of the recombination processes in Y 2 O 3 .…”