Band alignment at <italic>β</italic>-(Al<italic>x</italic>Ga1−<italic>x</italic>)2O3/<italic>β</italic>-Ga2O3 (100) interface fabricated by pulsed-laser deposition

High-quality <italic>β-</italic>(Al<italic>x</italic>Ga1−<italic>x</italic>)2O3 (<italic>x</italic> = 0–0.37) films were epitaxially grown on <italic>β</italic>-Ga2O3 (100) substrates by oxygen-radical-assisted pulsed-laser deposition with repeating alternate ablation of single crystals of <italic>β</italic>-Ga2O3 and <italic>α</italic>-Al2O3. The bandgap was tuned from 4.55 ± 0.01 eV (<italic>x</italic> = 0) to 5.20 ± 0.02 eV (<italic>x</italic> = 0.37), where bowing behavior was observed. The band alignment at the <italic>β-</italic>(Al<italic>x</italic>Ga1−<italic>x</italic>)2O3/<italic>β</italic>-Ga2O3 interfaces was found to be type-I with conduction- and valence-band offsets of 0.52 ± 0.08 eV (0.37 ± 0.08 eV) and 0.13 ± 0.07 eV (0.02 ± 0.07 eV) for <italic>x</italic> = 0.37 (0.27), respectively. The large conduction-band offsets are ascribed to the dominant contribution of the cation-site substitution to the conduction band. [ABSTRACT FROM AUTHOR]