A high resolution scanning electron microscope for in situ investigation of swift heavy ion induced modification of solid surfaces

A new in situ high resolution electron microscope (HRSEM) setup has been designed and integrated into the materials science beamline (M-branch) of the universal linear accelerator at Gesellschaft fuer Schwerionenforschung, Darmstadt for in situ investigations of swift heavy ion induced surface modifications. Special ports for in situ experiments are installed at the HRSEM chamber to connect it to the high vacuum beamline, which is equipped with suitable beam control and shaping devices. In order to demonstrate the feasibility and power of this new instrument, first experiments were performed on a 50-nm-thick Fe2O3 film on Si substrate, which exhibited submicrometer size holes due to irradiation induced dewetting in a previous experiment. We have demonstrated that with our new instrument, the development of individual dewetting holes as a function of the ion fluence can be investigated and even the interaction between them can be studied. To illustrate pattern formation during grazing incidence, 3.6 MeV/u 131Xe ion irradiation was carried out on a 25-nm-thick NiO film on SiO2/Si at a tilt angle of 75 deg. The SEM image sequence recorded during the experiment reveals the development of a lamellaelike structure also seen before in ex situ experiments. With our new in situ setup, however, we are able to not only investigate the overall average pattern formation, but also to track the formation and decay of individual linking structures, which would be hardly possible in a standard ex situ experiment.