No abstract

The adsorption and thermal decomposition of N 2 H 4 and CH 3 N 2 H 3 on Si(111)-7x7 were investigated using XPS, UPS and HREELS in the 120-1350 K surface temperature range. Both molecules were partially dissociated into N 2 Hx or CH 3 N 2 Hx (x=2,3) species with the N-N bond parallel or nearly parallel to the surface as they adsorbed on the surface at 120 K, especially at lower dosages (e.g., < 0.2 L) and more so for N 2 H 4 than CH 3 N 2 H 3 . This was evidenced by the appearance of the Si-H vibration at 255 meV in the HREEL spectra and by the relatively larger FWHMs of the Nls XPS and the n+,n-molecular UPS peaks. When a -0.4 L N 2 H 4 or CH 3 N 2 H 3 dosed sample was annealed to -500 K, significant desorption of the molecules occurred as well as further dissociation of the N-H bonds. Above -600 K, the N-N bond began to break leading to the formation of NHx (x=1,2) species for both