Structural, Optical, and Electrical Characterization of β‐Ga2O3 Thin Films Grown by Plasma‐Assisted Molecular Beam Epitaxy Suitable for UV Sensing

β ‐Ga 2 O 3 thin films were grown on c‐plane sapphire substrates by plasma‐assisted molecular beam epitaxy. The films were grown using an elemental gallium source and oxygen supplied by an RF plasma source. Reflection high‐energy electron diffraction (RHEED) was used to monitor the surface quality in real time. Both in situ RHEED and ex situ X‐ray diffraction confirmed the formation of single crystal β ‐phase films with excellent crystallinity on c‐plane sapphire. Spectroscopic ellipsometry was used to determine the film thicknesses, giving values in the 11.6–18.8 nm range and the refractive index dispersion curves. UV‐Vis transmittance measurements revealed that strong absorption of β ‐Ga 2 O 3 starts at ∼270 nm. Top metal contacts were deposited by thermal evaporation for I‐V characterization, which has been carried out in dark, as well as under visible and UV light illumination. The optical and electrical measurements showed that the grown thin films of β ‐Ga 2 O 3 are excellent candidates for deep‐ultraviolet detection and sensing.