Deposition of Gallium Oxide Nanostructures at Low Substrate Temperature by Chemical Vapor Deposition

Abstract

Semiconductor nanostructures (NSs) are usually synthesized at short source-substrate distances where the substrate temperature is high using the chemical vapor deposition (CVD) technique. Herein, we report for the first time the growth of -Ga2O3 NSs at low substrate temperature ∼260 °C in a CVD system when gallium (III) oxide powder was reduced to Ga vapor at 1000 °C under hydrogen atmosphere. The polycrystalline nature of the Ga2O3 NSs was confirmed by high-resolution X-ray diffraction (HR-XRD) analysis. Appearance of additional diffraction planes, increasing X-ray diffraction signal strength and shift of 2θ to smaller angles was observed with increasing hydrogen supply in the reactor. Field-emission scanning electron microscope (FE-SEM) revealed different morphologies with increasing amount of Ga2O3 on the substrate. Elemental analysis by using energy dispersive X-ray spectroscopy (EDX) showed increasing Ga atoms, and Ga/O atomic ratio with increase in hydrogen gas flow rate. Optical reflectance measurements by UV–vis-NIR spectrophotometer revealed optical bandgaps ranging from 4.94 to 4.82 eV, attributed to increasing film compactness, Ga/O and oxygen vacancies on the prepared films.