A Structural and Ellipsometric Investigation of Thin Gallium Oxide Layers Deposited on Si by Means of Laser Deposition

Abstract

The morphology of Ga₂O₃ layers deposited on a silicon substrate by pulse laser deposition is studied using scanning electron microscopy in the thickness range of 30–200 nm. Using spectroscopic ellipsometry in the wavelength range from 250 to 900 nm, the thickness of layers and dispersion of their optical parameters (complex pseudodielectric function ε, refractive and absorptive indices) have been determined and the fraction of voids has been estimated in the scope of the Bruggeman effective medium approximation. In the spectrum of the imaginary part ε₂, there is observed an increase in values in the region of energy E = 4.8 eV corresponding to the direct interband transition in the Ga₂O₃ structure. X-ray structure analysis showed the presence of peaks typical for the β-Ga₂O₃ structure. The results of the investigations can be used for the formation of wide-bandgap gallium oxide layers in developing devices of power electronics and in creating optoelectronic devices for the UV range.