Epitaxial growth and electrical properties of γ-Al2O3 films on β-Ga2O3(010) substrates were investigated regarding the prospect of a gate oxide in a β-Ga2O3-based MOSFET. The γ-Al2O3 films grew along the  direction and inherited the oxygen sublattice from β-Ga2O3 resulting in the unique in-plane epitaxial relationship of γ-Al2O3=110 k β-Ga2O3. We found that the γ-Al2O3 layer had a band gap of 7.0 eV and a type-I band alignment with β-Ga2O3 with conduction-and valence-band offsets of 1.9 and 0.5 eV, respectively. A relatively high trap density (2 × 1012 cm-2 eV-1) was found from the voltage shift of photoassisted capacitance-voltage curves measured for a Au/γ-Al2O3/β-Ga2O3 MOS capacitor. These results indicate good structural and electric properties and some limitations hindering the better understanding of the role of the gate dielectrics (a γ-Al2O3 interface layer naturally crystallized from amorphous Al2O3) in the β-Ga2O3 MOSFET.
ASJC Scopus subject areas
- Physics and Astronomy(all)