Temperature dependence of the UPS and HREELS of HN₃ and DN₃ on Si(110)

HN₃ was used for the first time as a nitrogen source for nitridation of Si surfaces. Its interaction with Si(110) was studied with HREELS and UPS at temperatures between 120 and 1350 K. HN₃ was found to adsorb molecularly on the Si surface at 120 K, as all molecular vibrational peaks, such as HN-NN stretching at 150 meV, HNN = N stretching at 265 meV and H-NNN stretching at 414 meV, were clearly observed in HREEL spectra. A similar HREELS study of DN₃ was carried out to confirm some of the EELS assignments. Upon warming up to 220 K, HN₃ started to dissociate into N₂ and NH, which further dissociated to give N and H as the surface was annealed from 580 to 800 K. H adatoms were observed to desorb at T > 800 K, while N remained on the surface, forming Si₃ N₄ at T ≅ 1350 K.