THE EFFECT OF PREPARATION CONDITIONS ON THE ELECTRICAL CONDUCTIVITY OF THIN FILMS OF (Y0.06Ga0.94)2О3

Ihor Kukharskyy, Iryna Kofliuk, Ivanna Medvid, Ihor Kuz, Oleh Bordun

Abstract


Background. β-Ga2O3 gallium oxideis a promising wide-bandgap semiconductor widely used in optoelectronic and sensing applications. The electrical conductivity of thin films strongly depends on their structural quality, defect states, and post-deposition treatment conditions. In polycrystalline films, grain boundaries and defect complexes significantly affect charge transport mechanisms. The objective of this study is to investigate the influence of annealing atmospheres on the structural, morphological, and electrical properties of (Y0.06Ga0.94)2О3 thin films.

Materials and Methods. Thin films of (Y0.06Ga0.94)2О3 with thicknesses of 0.3–1.0 μm were deposited by RF ion-plasma sputtering onto fused quartz substrates. Post-deposition annealing was carried out in oxygen and argon atmospheres at 1000–1100 °C, and in hydrogen at 600–650 °C. Structural properties were analyzed using X-ray diffraction, while surface morphology was examined by atomic force microscopy. Electrical conductivity was measured in the temperature range of 300–450 K, and activation energies were determined from temperature-dependent conductivity data.

Results and Discussion. X-ray analysis confirmed the formation of films in the monoclinic β-Ga2O3 phase, with enhanced crystallinity and preferred orientation after annealing in oxygen. It has been established that freshly deposited films have a high resistivity (ρ > 10¹¹ Ω·cm), which decreases with increasing temperature and after annealing. Oxygen annealing resulted in activation energy of ~0.87 eV, while argon annealing produced higher values (~1.38 eV in 300–400 K range), indicating deeper donor levels associated with oxygen vacancies. Hydrogen annealing significantly reduced resistivity (~10⁸ Ω·cm) and activation energy (~0.40 eV), attributed to shallow donor states.

Conclusion. The electrical conductivity of (Y0.06Ga0.94)2О3 thin films is governed by defect-related donor levels formed during annealing. Oxygen and argon atmospheres promote deep donor states, while hydrogen enhances shallow donor formation, leading to improved electrical conductivity.

Keywords: thin films, gallium oxide, crystalline structure, impurities, electrical conductivity


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DOI: http://dx.doi.org/10.30970/eli.33.13

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