Impact of erbium (Er) doping in structural, optical and electrical properties of Ga2O3 nanostructures/Si heterojunction

In the current study, we report the growth of rare earth Er-doped Ga₂O₃ nanostructures on Ga₂O₃- seeded Si substrate by employing chemical bath deposition (CBD) and RF magnetron sputtering techniques. A thin layer (~50 nm) of Ga₂O₃ is deposited on p-Si substrate with the optimize deposition temperature and Ar:O₂ flow rate to create a favourable template for growing high quality nanostructures on it. After growing the Er-doped Ga₂O₃ nanostructures, thermal annealing is performed at 800°C to achieve thermodynamically stable β-phase of Ga₂O₃. The effect of Er doping on structural, optical and luminescence properties of Ga₂O₃ nanostructures has been successfully investigated by employing FEGSEM, XRD, UV-VIS and PL. XRD studies confirms the polycrystalline β-phase monoclinic structure of Ga₂O₃ for both undoped and Er-doped nanostructures with dominant <-111> plane. Top view images of FEGSEM depict the large area growth of rod/wire like structures of Ga₂O₃ on thin Ga₂O₃ deposited Si substrate and confirm the formation of heterojunction between Ga₂O₃ and Si. Deconvoluted PL spectra shows two broad peaks within the wavelength range of 260 nm to 460 nm, which are associated with near band emission and three different types of oxygen vacancies present in β-Ga₂O₃, respectively. The change in optical absorbance and corresponding energy band gap of undoped and Er-doped nanostructures are analysed in detail by using UV-VIS spectroscopy and such energy bandgap values lie with the range of 4.4 eV-4.7 eV. Finally, current-voltage characteristics of undoped and Er-doped Ga₂O₃/Si heterojunction has been studied and such heterojunctions can be a potential candidate for the fabrication of several optoelectronic devices as well as high power applications.