Instituto Superior Técnico, Universidade de Lisboa
Atmospheric Measurement Facilities
Space Environment Test Facilities
Nuclear Research Facilities
Earth and Environmental Sciences
Biological and Medical Sciences
Physics, Astronomy, Astrophysics and Mathematics
Chemistry and Material Sciences
Measurements: Ion-beam analysis; Modification of materials: ion implantation; Evaluation: evaluation of IBA spectra; Research infrastructures: EG2R, NIK; Spectroscopic ellipsometer; Software development for control and evaluation: RBX, DEPTH, RBS-MAST.
Sensitive elemental analysis completed with a quantitative chemical analysis is indispensable for preparing good quality thin layers. Detailed knowledge of the interfaces within a layered structure can play a decisive role in ensuring the desired functional properties of a thin layer structure. Depth profiling is one of the most powerful methods of determining the depth distribution of atomic composition. It can be performed by ion sputtering, where particles are removed from the surface. A Secondary Neutral Mass Spectrometer (SNMS) supplemented with a Secondary Ion Mass Spectrometer (SIMS) is an ideal piece of equipment for performing quantitative depth profile analysis of thin films. While SNMS can be used to produce high depth resolution, SIMS is suitable for producing high lateral resolution. SNMS using electron gas post-ionization is ideally suited to quantitative elemental and depth profiling analyses of any material. Minimal matrix effects and no influence due to preferential sputtering allow very accurate material analysis. Since the sample current is highly uniform over the entire analysed area and the sputtering energies are low (a few 100 eV), high depth resolution (1 nm) can be achieved by SNMS.
The main parameters of the accelerator: Terminal voltage range 1-3,5 MV; Ion mass-energy product 56 MeV x AMU/e2; Energy stability 1 keV; Maximum beam intensity, direct 50 uA; Maximum beam intensity, analyzed 10 uA; Ion source inductively coupled RF source; Ion range H+, D+, He+, C+, N+, O+, Ne+. There are five available beamlines, of which atomic physics, nuclear physics, nuclear astrophysics experiments are installed as well as the Laboratory of Ion Beam Applications.
The investigations of materials by nuclear methods is based on the ion beam facilities of our institute (5 MeV Van de Graaf accelerator, Heavy Ion cascade implanter, proton microbeam and ion beam analytical equipments). The main application areas are biological, material, environmental, archeological and cultural heritage research. Our laboratory collaborates with research institutes of HAS and universities. Although the ion accelerators are part of HIPP, they are, at the same time, also individual infrastructures. Applied ion beam analytical methods are: Rutherford backscattering(RBS), combined with channeling (RBS/channeling), Elastic recoil detection analysis (ERDA), nuclear reaction analysis(NRA), proton induced characteristic X-ray spectroscopiy (PIXE), Scanning transmission ion microscopy (STIM). Applied sample preparation and modification method is ion implantation.
In the KFKI Research Institute for Particle and Nuclear Physics (KFKI RMKI) an MBE system was installed by MECA 2000. According to the needs of applied nuclear physics a special 57Fe enriched source was installed amongst the 12 atom sources in the growth chamber. The 57Fe effusion cell allows for isotope selective multilayer growth, which is a unique tool for depositing multilayers with local probes and investigating them by the Mössbauer effect. The 12 sources are located in two electron-guns and four effusion cells allowing for co-evaporation and multilayer deposition. Each e-gun contains four-four crucibles allowing for the growth of different systems without the need of venting the chamber. At the present moment the sources are: Au, Ag, Al, 57Fe, Co, Ni, Cr, Fe, Cu, V, Pd, Pt, 62Ni. The ultrahigh vacuum (UHV) system consists of a load-lock, a preparation chamber, a transport tube and a growth (main) chamber. A UHV suitcase can be mounted on the preparation chamber, capable of transporting a single sample in ultrahigh vacuum. The system was designed to hold substrates of maximum 2-inch diameter. The sample preparation begins with external substrate cleaning. After introducing the sample to the transport tube (trough the load-lock) an optional pre-treatment follows in the preparation chamber. In the majority of cases the substrate is annealed (UHV cleaning), then the substrate is moved to the main chamber, where the growth process starts. The sources (effusion cells and e-guns) are started, the cryoshroud activated (to get better vacuum), and the sample is rotated for better homogeneity. The thickness of the layers is monitored by quartz crystal monitors, while the surface structure is deduced from RHEED (Reflection High-Energy Electron Diffraction) images. At the present moment there is no possibility of further in-situ analysis, but the system is expandable trough the transport tube.
The Laboratory is operated by the Section of Ion Beam Physics of ATOMKI. The experimental facilities are suitable for atomic and nuclear physics and materials science applications (including proton beam micromachining), and for analytical studies (PIXE, RBS, NRA, PIGE, DIGE) based on MeV ion beams provided by the VdG-5 accelerator. Facilities: - Nuclear microprobe (1x1 um2 focused beam, max. 2,5x2,5 mm2 scanned area, simultaneous X-ray (in two energy regions), particle- and gamma-detection; accurate charge determination; sample positioning by 5-axis goniometer) - MacroPIXE chamber (semiautomatic sample stage) - Nuclear reaction beamline (various holders for different samples) Other features: - X-ray-, gamma- and particle detectors with signal processors and data acquisition electronics, spectrum evaluation software and beam scanning software - X-ray fluorescence setup with a 60 kV excitation tube - General purpose optical microscope - Vacuum evaporator.