Nano analytic

PPToFMS (Plasma Profiling Time-of-Flight Massspectrometry) is a universal depth profiling tool that enables precise Time-of-Flight mass spectrometry (TOF MS) measurements of thin film structures with high throughput. This includes the precise determination of the composition of materials with a high depth resolution in the nm range. The depth profiling is achieved by forming a crater by plasma etching on the surface of the sample and then etching it vertically layer by layer and analyzing the formed ions by TOF MS. The required high sputtering rate is realized by the high ion density of the glow discharge plasma. The device ensures TOF mass spectrometry measurements on inorganic materials. Application examples include the analysis of dopants in semiconductors, for instance in quantum wells (incorporation behavior of dopants, diffusion), the detection and identification of surface contaminants. The device has a high level of availability as it is one of the key facilities at the new LENA research center, used in parallel by several groups in physics, electrical engineering and chemistry.

Worldwide up to now only two more similar setups were installed. Ours is the newest and most sophisticated one.

• Plasma Profiling Time-of-Flight Mass Spectrometry for Fast Elemental Analysis of Semiconductor Structures with Depth Resolution in the Nanometer Range. H. Spende, C. Margenfeld, T. Meyer, I.M. Clavero, H. Bremers, A. Hangleiter, M. Seibt, A. Waag, A. Bakin. 2020, Semiconductor Science and Technology  https://doi.org/10.1088/1361-6641/ab6ac0
• Contact:  Prof. Bakin

In conventional light microscopy, the resolution is limited by diffraction to about half the wavelength of the light used for imaging, meaning that structures below ~ 200 nm cannot be resolved. Recently, several approaches for superresolution fluorescence microscopy (or nanoscopy) have been developed, which are not limited by difraction:

One prominent example of these superresolution techniques is STED (STimulated Emission Depletion) microscopy: Based on a confocal microscope, a second, red-shifted laser is overlayed onto the excitation focus. Via stimulated emission, the excited fluorophores are switched off. By modifying the focus of the redshifted laser to have a doughnut shape, only fluorophores in the outer region of the exciting focus are swichted off, the ones in the very center remain active. By scanning this size-reduced, effectively exciting focus through the sample, a diffraction-unlimited fluorescence image can be obtained.

In LENA, we have a commercial STED-microscope available, which can be used for the examination of both biological and technical samples.

Contact: Dr. Birka Lalkens