A TPD, HREELS, and XPS study of electron-induced deposition of germanium on Si(100)

The decomposition of digermane and deposition of germanium via electron irr adiation of digermane overlayers on Si(100) at 110 K was studied using temp erature programmed desorption (TPD), high resolution electron energy loss s pectroscopy (HREELS), and X-ray photoelectron spectroscopy (XPS). At high d igermane exposures, hydrogen TPD traces exhibit three peaks at 140, 575, an d 740 K, corresponding to desorption of molecularly adsorbed digermane, hyd rogen desorption from adsorbed germanium, and hydrogen desorption from the silicon monohydride state, respectively. HREELS spectra of Si(100) followin g high exposures to digermane, exhibit losses at 820 and 2050 cm(-1), and a shoulder at 2150 cm(-1), corresponding to the GeHx scissor, Ge-H stretchin g, and Si-H stretching vibrational modes, respectively. Electron irradiatio n (E = 150 eV) of digermane overlayers on Si(100) causes a decrease in the intensity of the 140-K TPD peak and an increase in the intensity of the 575 -K TPD peak, and a decrease in the intensity of the HREELS losses. The rela tive concentration of germanium on Si(100) (as determined by XPS) after ann ealing the surface to 200 K is at least 2 times higher on electron-irradiat ed surfaces than on surfaces that were not exposed to the electron beam. (C ) 1999 Published by Elsevier Science B.V. All rights reserved.