Equipment Surface Analysis
The characterisation of surfaces is of importance for many applied research fields such as e.g. materials sciences, catalysis, electrochemistry, biology or semiconductor technology. Depending on the question, investigations on the surface morphology, composition or trace analysis are carried out and can be combined with each other. Depth profile analysis can be used to provide information on possible enrichments of selements in near-surface regions in comparison to the bulk of the examined material.
Within the AIC AFM/STM, SEM/EDX, TOF-SIMS, XPS, UPS and AES as analytical techniques are available, as well as the corresponding expertise of Ao.Univ.Prof. Gernot Friedbacher, opens an external URL in a new window and his research group "Micro- and Nanoanalysis, opens an external URL in a new window", Ao.Univ.Prof. Herbert Hutter, opens an external URL in a new window and his research group "Physical Analysis, opens an external URL in a new window" and Dr. Annette Foelske, opens an external URL in a new window.
The Atomic Force Microscope (AFM) is based on “touching” a sample surface with a mechanical probe. The surfaces topography deflects the tip differently when the sample surface is scanned, yielding a topographic image of the surface up to atomic resolution. An AFM can be used to study a great variety of different samples (metals, semiconductors, insulators, polymers, biological samples and many more) under ambient conditions. Measurements may be made in-situ under liquids, thus allowing numerous processes to be monitored directly, such as corrosions or coating processes. The system is in addition to numerous other accessories also equipped with an add-on to perform conductivity measurements, this allows simultaneous recording of topography and the conductivity images of the sample surface.
The electron beam microprobe combines a scanning electron microscope (SEM) and an energy dispersive X-ray analysis system (EDS). The sample is bombarded with a finely focused electron beam, the emitted secondary electrons yield topographic images with resolutions of only a few nanometers. The backscattered electrons result in a contrast of different phases due to different average atomic numbers and the emitted X-ray radiation provides chemical information about the elements. The method is used to answer a variety of questions in material science but it is also applied to solve numerous other problems (environmental analysis, biology, medicine, etc.).
X-ray photoelectron spectroscopy (XPS) is a method used to determine the surfaces chemical composition for vacuum compatible materials. It is based on the external photoelectric effect, wherin photoelectrons are emitted from a solid by electromagnetic radiation. The binding energy of the photoelectrons is characteristic for each atom and allows assumptions about the atoms chemical environment. The information depth is a few nanometers (<10 nm). The used u-Focus system is a prototype designed by SPECS GmbH, Berlin, Germany. The analyser system (Phoisbos 150 WAL with 2D delay line detector) allows detection of the photoelectrons with an angular resolution. The monochromatic X-ray source (u-Focus 350, AlKa) permits focusing the X-ray beam with diameters between 500 um and 40 um.
Time-of-flight mass spectrometry, opens an external URL in a new window is a method for determining the elemental composition and chemical characterization of mass fragments. The high sensitivity of the method allows the detection of trace elements down to the ppb range. The 3D analysis allows the investigation of thin surfaces and thicker layers (a monolayer up to about 10 micrometers) with a depth resolution of < 1nm and a lateral resolution of < 100nm.
The Dektak Stylus Profilometer, opens an external URL in a new window is used to measure surface profiles. Steps of < 10 nm can be determined with a repetition rate of < 0.4 nm. The profilometer allows fast scanning over a wide range and the display of 3 dimensional surface profiles.