Optical properties of gallium oxide films deposited by electron-beam evaporation

Abstract

Thin films of gallium oxide were deposited by electron-beam evaporation on unheated substrates. Samples were deposited either without oxygen, or under an oxygen partial pressure of 5×10−4 mbar. The films were amorphous. Films deposited with oxygen were stoichiometric, whereas those deposited without oxygen were substoichiometric. The optical properties of the films were derived from measurements, at normal incidence, of transmittance and reflectance. Films deposited without oxygen had higher values of the refractive index and extinction coefficient. The energy gaps were 5.04 and 4.84 eV for films deposited with and without oxygen, respectively.

Light-emitting Ga-oxide nanocrystals in glass: a new paradigm for low-cost and robust UV-to-visible solar-blind converters and UV emitters

“…On the Ga-free sample we prepared with identical relative molar compositions of the other components -taken as a reference of the host matrix aer phase separation -we measure a refractive index n g ¼ 1.566 AE 0.001 at 632 nm. From n g and n c , assuming the latter be equal to the b-Ga 2 O 3 value of 1.93, 32 we calculate the size dependence of scattering-attenuated transmittance in Fig. 1f.…”

“…[43][44][45][46][47][48][49][50][51] Such a spread of values is related to the variability of oxygen stoichiometry in Ga-oxides, the larger the oxygen de-ciency, the smaller the effective bandgap. 32 Additional spread of E G values can be expected in NCs, in principle, from quantum connement (QC). However, such an effect was rarely registered, if any, in the optical absorption spectrum of Ga 2 O 3 .…”

How an oxide shell affects the ultraviolet plasmonic behavior of Ga, Mg, and Al nanostructures

“…The dielectric constants of Al, Mg, Al 2 O 3 , MgO, and Ga 2 O 3 have been taken from different sources in the literature [28,29], but the values for Ga were obtained in situ by spectroscopic ellipsometry [7] and confirmed by those reported in the literature [30]. Figure 2 plots the real and imaginary parts of the dielectric function = r +i i for the three metals and their corresponding oxides.…”

Plasmonics in the Ultraviolet with Aluminum, Gallium, Magnesium and Rhodium

“…Figure 2 shows the complex dielectric permittivity ( = r + i i ) of these metals and their corresponding oxides. The values of the complex dielectric permittivity have been taken from different sources in the literature [18,20,79]. Note the similar optical behavior shown by Mg and Al oxides, while Ga 2 O 3 shows absorption in the UV region above 3 eV.…”