INTERACTION OF GEH4 WITH THE GE(100)2X1 SURFACE

We present photoemission and LEED results concerning the interaction of decomposed germane (GeH4*) with a monocrystalline Ge(100)2 x 1 surface. As the sticking coefficient of undecomposed germane on Ge(100) is very weak, we catalytically decompose the germane molecules with a hot tungsten filament. Germanium substrates are heated by the Joule effect in the 20-500 degrees C temperature range aml exposed to either catalytically decomposed or undecomposed germane. The crystalline quality of the deposited films is controlled by low energy electron diffraction (LEED) and angle resolved ultraviolet photoelectron spectroscopy (ARUPS). We compare our ARUPS spectra with spectra resulting from the hydrogenation of the Ge(100) surface by means of atomic hydrogen (H*). After exposure of the Ge(100) surface to GeH4* at room temperature (RT), the deposited Ge films are submitted to annealings up to 250 degrees C. At RT, the deposited Ge film is amorphous with an ARUPS signature characteristic of a polygermane. After annealing at 250 degrees C, we recover the LEED pattern of the Ge(100)2 x 1 reconstruction. No chemical shift has been evidenced by means of X-ray photoelectron spectroscopy (XPS) between the Ge 3d core level of the deposited Ge film or Ge(100) substrate.