In situ growth monitoring of distributed GaN–AlGaN Bragg reflectors by metalorganic vapor phase epitaxy

A series of distributed GaN-AlGaN Bragg reflectors (DBR) has been grown on $Al2O3(0001)$ substrates by metalorganic vapor phase epitaxy. The growth of the GaN template as well as of the $GaN–AlxGa1−xN$ quarter-wave stack has been monitored by laser reflectometry. The evolution of the in situ reflectivity as well as DBR reflection spectra are discussed as function of the $AlxGa1−xN$ composition x.