• Haque, Aman
• Hassa, Anna
• Xia, Xinyi
• Grundmann, Marius
• Fares, Chaker
• Pearton, Stephen
• Al-Mamun, Nahid Sultan
• Wenckstern, Holger Von
• Ren, Fan

Abstract

<jats:p>X Ray Photoelectron Spectroscopy was used to measure valence band offsets for Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> deposited by Atomic Layer Deposition on <jats:italic>α</jats:italic>-(Al<jats:sub>x</jats:sub>Ga<jats:sub>1-x</jats:sub>)<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> alloys over a wide range of Al contents, x, from 0.26–0.74, corresponding to a bandgap range from 5.8–7 eV. These alloys were grown by Pulsed Laser Deposition. The band alignments were type I (nested) at x &lt;0.5, with valence band offsets 0.13 eV for x = 0.26 and x = 0.46. At higher Al contents, the band alignment was a staggered alignment, with valence band offsets of − 0.07 eV for x = 0.58 and −0.17 for x = 0.74, ie. negative valence band offsets in both cases. The conduction band offsets are also small at these high Al contents, being only 0.07 eV at x = 0.74. The wide bandgap of the <jats:italic>α</jats:italic>-(Al<jats:sub>x</jats:sub>Ga<jats:sub>1-x</jats:sub>)<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> alloys makes it difficult to find dielectrics with nested band alignments over the entire composition range.</jats:p>

Topics

• pulsed laser deposition
• photoelectron spectroscopy
• atomic layer deposition