Exciton luminescence in AlN triggered by hydrogen and thermal annealing

摘要

Exciton recombination bands in homoepitaxial AlN layers are strongly dependent on the presence of hydrogen. By thermal treatment under hydrogen-free and hydrogen-rich ambient, respectively, several sharp bound exciton lines are modulated in intensity reversibly. In contrast, the exciton bound at the neutral donor silicon remains unaffected. The mechanism causing these effects is most probably hydrogen in- and out-diffusion into the AlN sample. The main factor determining hydrogenation of AlN layers is found to be molecular H_2 in contrast to NH_3. We find hints that carbon incorporation into AlN may be closely related with that of hydrogen. Besides photolumines-cence spectra of exciton bands, our model is supported by theoretical reports and comparison to the case of hydrogen in GaN.