High-reflectivity GaN GaAlN Bragg mirrors at blue green wavelengths grown by molecular beam epitaxy

Highly-reflective GaN/GaAlN quarter-wave Bragg mirrors, designed to be cent ered at blue/green wavelengths, have been grown by molecular beam epitaxy. The reflectivity for a mirror centered at 473 nm was as high as 93% and the bandwidth reached 22 nm. Detailed x-ray diffraction measurements allowed u s to characterize the structural parameters of the Bragg mirrors. We show t hat, in spite of substantial strain relaxation occurring in our samples, hi gh reflectivity is still possible. In addition, we show that growth interru ption at the heterointerfaces is crucial for achieving high reflectivities. (c) 1999 American Institute of Physics. [S0003-6951(99)03824-3].