Preparation, Chemical Composition, and Optical Properties of ( β –Ga 2 O 3 Composite Thin Films)/(GaS x Se 1−x Lamellar Solid Solutions) Nanostructures

GaS x Se 1−x solid solutions are layered semiconductors with a band gap between 2.0 and 2.6 eV. Their single crystals are formed by planar packings of S/Se-Ga-Ga-S/Se type, with weak polarization bonds between them, which allows obtaining, by splitting, plan-parallel lamellae with atomically smooth surfaces. By heat treatment in a normal or water vapor-enriched atmosphere, their plates are covered with a layer consisting of β –Ga 2 O 3 nanowires/nanoribbons. In this work, the elemental and chemical composition, surface morphology, as well as optical, photoluminescent, and photoelectric properties of β –Ga 2 O 3 layer formed on GaS x Se 1−x (0 ≤ x ≤ 1) solid solutions (as substrate) are studied. The correlation is made between the composition (x) of the primary material, technological preparation conditions of the oxide-semiconducting layer, and the optical, photoelectric, and photoluminescent properties of β –Ga 2 O 3 (nanosized layers)/GaS x Se 1−x structures. From the analysis of the fundamental absorption edge, photoluminescence, and photoconductivity, the character of the optical transitions and the optical band gap in the range of 4.5–4.8 eV were determined, as well as the mechanisms behind blue-green photoluminescence and photoconductivity in the fundamental absorption band region. The photoluminescence bands in the blue-green region are characteristic of β –Ga 2 O 3 nanowires/nanolamellae structures. The photoconductivity of β –Ga 2 O 3 structures on GaS x Se 1−x solid solution substrate is determined by their strong fundamental absorption. As synthesized structures hold promise for potential applications in UV receivers, UV-C sources, gas sensors, as well as photocatalytic decomposition of water and organic pollutants.