AVS 45th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS2-WeA

Paper SS2-WeA2
Electron Induced Deposition of Germanium on Si(100): TPD, XPS, and HREELS Study

Wednesday, November 4, 1998, 2:20 pm, Room 309

Session: Photochemistry and Deposition
Presenter: J. Lozano, University of Texas, El Paso
Authors: J. Lozano, University of Texas, El Paso
J.H. Craig, University of Texas, El Paso
J.H. Campbell, University of Texas, El Paso
Correspondent: Click to Email
Temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and high resolution electron energy loss spectroscopy (HREELS) were used to investigate the effects of an electron beam on Si(100) dosed with digermane at 110 K. At high digermane coverages (>1 ML), three peaks appear on hydrogen TPD traces at 140 K, 575 K, and 740 K. The peak at 140 K corresponds to desorption of hydrogen from molecular overlayers of digermane, as confirmed by the desorption of digermane fragments at 140 K. The TPD features at 575 K and 740 K correspond to hydrogen desorption from surface germanium and from silicon, respectively. The vibrational losses at 820 and 2040 cm@super -1@ in the HREELS data obtained from digermane-covered Si(100) indicate the presence of germanium hydride species on the surface. The formation of the silicon monohydride state is evident by the high-energy broadening of the loss feature at 2040 cm@super -1@. Upon exposure of the highly dosed surface to an electron beam (maximum current density of 9µA/cm@super 2@), the intensity of the low temperature TPD peak at 140 K decreases, while the intensity of the peak at 575 K increases. XPS data show an increase on the relative surface concentration of germanium following electron irradiation of the digermane overlayers. Annealing the surface to 200 K does not decrease the relative concentration of germanium on the electron-irradiated surface. Electron irradiation of digermane/Si(100) at low digermane exposures does not have any detectable effects. These results indicate that the electron beam dissociates the digermane molecular overlayers and deposits germanium on the surface.