Growth and characterization of (Ga1−xGdx)2O3 by pulsed laser deposition for wide bandgap applications

Thin film wide bandgap Ga 2 O 3 based alloys are important for applications in high power electronic, gate dielectric, deep UV photonics, spintronics and nuclear detectors. Epitaxial (Ga 1 − x Gd x ) 2 O 3 thin films with varied x were successfully grown on Al 2 O 3 (0001) substrates to tune the materials properties using variations in the growth parameters. High growth temperatures favor the formation of the monoclinic β- ( Ga 1 − x Gd x ) 2 O 3 phase; the higher the Gd composition, the greater the growth temperature required for high quality crystalline thin films. Incorporation of Gd into Ga 2 O 3 crystal expands the crystal lattice causing peak shift toward lower angle. UV–vis measurements demonstrate a slight red shift of the bandgap (4.99–4.82 eV) in comparison with the pure β-Ga 2 O 3 . Extracted refractive index from surface ellipsometry were in the range of 1.86–1.92. XPS spectroscopy confirmed the presence of Gd 3+ oxidation states. Current voltage measurements demonstrate Gd doping increases the resistivity of the samples. Finally, our findings are confirmed by density functional study.