Comprehensive ellipsometric analysis of linear and nonlinear optical properties of GaAs for optoelectronic and communication applications

Abstract Gallium arsenide (GaAs), a widely studied semiconductor, has attracted sustained scientific interest for decades due to its critical role in optoelectronic devices. In this study, we present an extensive analysis of both linear and nonlinear optical properties of GaAs crystals, measured using ellipsometry over a broad spectral range. Ellipsometric data were interpreted using a sample-air optical model, with dielectric function, refractive index, extinction coefficient, optical conductivity, surface and volume energy loss function spectra plotted and analyzed. From the absorption coefficient data, the direct bandgap was revealed as 1.44 eV. The spectral dependencies of the refractive index and the real part of the dielectric function were explored through the Wemple-DiDomenico and Spitzer-Fan models, respectively, revealing key optical constants. Additionally, parameters like the ratio of carrier concentration to effective mass were obtained, offering insights into the material’s optoelectronic potential. The nonlinear optical parameters of GaAs were also evaluated, underscoring its relevance for advanced optoelectronic applications. The crystallinity and structural properties of the GaAs crystals, grown using the Bridgman method, were confirmed through X-ray diffraction analysis, further validating the material’s quality.