An SEM and STM investigation of surface smoothing in 130 MeV Si-irradiatedmetglass MG2705M

Metglass MG2705M foils of about 17 mu m thickness were irradiated at 90 K b y 130 MeV Si-28 ions, up to a fluence of 1.154 x 10(16) ions cm(-2). The su rface modifications induced by irradiation have been examined by scanning e lectron microscopy (SEM) and scanning tunnelling microscopy (STM). It has b een observed that smoothing of the sample surface is evident in both SEM an d STM micrographs. The SEM pictures show a decrease in the heights of the ' hills' and filling up of the 'valleys' on micrometre length scales. The STM pictures, on the other hand, show smoothing of scratchlike surface disorde rs at nanometre length scales. However, the electronic energy loss S-e, of 5.75 keV nm(-1), does not lead to detectable track diameters, in agreement with the existing results. The observations have been attributed to a large electronic energy deposition due to high fluence, and a subsequent local s hear relaxation of the near surface atoms. The theory of shear Bow mechanis m has been extended further to explain the results.