On the origin of blue emission from As-doped GaN

As-doped GaN films have been grown by plasma-assisted molecular beam epitax y and their properties investigated using atomic force microscopy, X-ray di ffraction and photoluminescence (PL) spectroscopy. The structural propertie s of the As-doped GaN films improve with increasing sample thickness. The r oom temperature PL is dominated by a strong blue emission band, exhibiting multiple peaks centered at 2.6 eV. The number of peaks increases monotonica lly with sample thickness. From this we conclude that the multiple peaks in the blue emission band of As-doped GaN samples arise mainly from optical i nterference effects. However, the possibility of several transitions involv ing As being responsible for the blue emission process cannot be excluded.