van der Waals epitaxy of ferroelectric <i>ε</i> -gallium oxide thin film on flexible synthetic mica
Yuta Arata, Hiroyuki Nishinaka, Daisuke Tahara, Masahiro Yoshimoto
Abstract
Abstract This study demonstrates the formation of the van der Waals epitaxy of the ε -gallium oxide (Ga 2 O 3 ) thin film on cleaved synthetic mica via mist chemical vapor deposition. Orthorhombic ε -Ga 2 O 3 (001) was epitaxially grown on synthetic mica (001). The analysis using transmission electron microscopy revealed an in-plane orientation of ε -Ga 2 O 3 [010] ∣∣ synthetic mica [010]. However, the most thermodynamically stable β -Ga 2 O 3 was grown at the film-substrate interface. The optical direct bandgap of the ε -Ga 2 O 3 thin film grown by van der Waals epitaxy was estimated to be 5.0 eV, which was the same as for the heteroepitaxially grown ε -Ga 2 O 3 thin film on other substrates. Besides, after ε -Ga 2 O 3 thin film was grown on the synthetic mica substrates that are cleaved sufficiently thin, the sample could be bent or cut with scissors. These results denote that the epitaxial ε -Ga 2 O 3 thin films grown by van der Waals epitaxy can be applied to flexible electronics.