Growth of β‐Ga 2 O 3 on Al 2 O 3 and GaAs using metal‐organic vapor‐phase epitaxy

Epitaxial layers of monoclinic β‐Ga 2 O 3 were successfully grown on (0001) sapphire and ( $ \bar 1 $ 11) As GaAs substrates using metal‐organic vapor‐phase epitaxy (MOVPE). Triethylgallium (TEGa) and N 2 O were used as precursors for gallium and oxygen, respectively. Growth conditions could be determined, where β‐Ga 2 O 3 grows epitaxially on c ‐plane sapphire and ( $ \bar 1 $ 11) As GaAs substrates. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) measurements identify a epitaxial relationship with ( $ \bar 2 $ 01) β‐Ga 2 O 3 || (0001) sapphire and ( $ \bar 2 $ 01) β‐Ga 2 O 3 || ( $ \bar 1 $ 11) As GaAs. The observed sixfold rotational in‐plane symmetry results from differently oriented rotational domains of monoclinic β‐Ga 2 O 3 with twofold symmetry. Thin films deposited on substrates of other orientation show the formation of the low‐temperature modification α‐Ga 2 O 3 . Optical transmission spectra measured in the spectral range from 200 nm to 2000 nm show a well‐distinct absorption edge at about 5 eV for layers grown on c ‐ and a ‐plane sapphire. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)