Alternative substrates for gallium nitride epitaxy: photoluminescence and morphological investigations

Gallium nitride films grown by molecular beam epitaxy (MBE) on (0001) sapphire, lithium gallate and gallium arsenide (111)B substrates have been characterized using atomic force microscopy and photoluminescence spectroscopy. Inhomogeneities in the sapphire-based material are further explored via fluorescence imaging. Layers grown on GaAs substrate are shown to display superior luminescence properties and excellent surface morphology.