Microanalysis of β-(Al_xGa_1−x )₂O₃ Films Grown by MOCVD

A combined microanalysis and optical study of β-(Al_xGa_1−x )₂O₃ films grown on sapphire via metalorganic chemical vapour deposition, with thickness 350–1000 nm and Al fraction (x) from 0% to 45%, is presented. Al incorporation in the films showed a linear relation with nominal Al composition calculated from precursor flow rate, and the optical bandgap increased from 4.96 eV to 5.44 eV with a bowing parameter of 1.7 ± 0.5 eV. A high Al fraction led to reduced crystallinity, increased surface roughness, and diminished cathodoluminescence intensity. The topography revealed elongated surface features that evolved with Al content, and luminescence spectra exhibited a blueshift in peak emission attributed to the widening of the bandgap. These findings highlight the trade-off between bandgap tuning and material quality, informing future growth strategies for future electronic and optical devices.