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

Abstract

The decomposition of digermane and deposition of germanium via electron irradiation of digermane overlayers on Si(100) at 110 K was studied using temperature programmed desorption (TPD), high resolution electron energy loss spectroscopy (HREELS), and X-ray photoelectron spectroscopy (XPS). At high digermane exposures, hydrogen TPD traces exhibit three peaks at 140, 575, and 740 K, corresponding to desorption of molecularly adsorbed digermane, hydrogen desorption from adsorbed germanium, and hydrogen desorption from the silicon monohydride state, respectively. HREELS spectra of Si(100) following high exposures to digermane, exhibit losses at 820 and 2050 cm −1, and a shoulder at 2150 cm −1, corresponding to the GeH x scissor, Ge–H stretching, and Si–H stretching vibrational modes, respectively. Electron irradiation ( 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 relative concentration of germanium on Si(100) (as determined by XPS) after annealing the surface to 200 K is at least 2 times higher on electron-irradiated surfaces than on surfaces that were not exposed to the electron beam.