Ion beams techniques are nowadays indispensable and valuable tools for research and technology. They are widespread applied for the fabrication of microelectronics devices, the coating of surfaces, the modification and synthesis of novel materials, the elemental analysis of materials, artwork and antiques, archeological artefacts or biological samples, the application for medical tumor therapy and the sensitive dating by accelerator mass spectoscopy.
Our group operates a variety of different ion accelerators providing ion beams with energies ranging from few electron Volts up to several million electron volts for materials synthesis modification and analysis. We also develop novel accelerator components and novel ion beam techniqies for different specific applications.
This is a brief overview of some of the currently running research projects of the ion beam and nuclear solid state physics group. For more information on or a bachelor/master theses within these projects please contact us.
Supported by: DFG, BMBF University of Göttingen
Ultra-low energy ion implantation of 2D materials
Ultra-low energy ion implantation into 2D materials can be done using a world-wide unique mass selected low energy ion beam deposition system (MSIBD system).
We can implant graphene sheets on various substrates as well as graphene on TEM grids with mass selected ultra low energy mass selected ions under UHV conditions (P < 10-6 Pa) Ion energy:down to 20 eV rather uniform over an area of about 2 cm2 and a beam current up to several µA. Typical Ion Fluences are: 1E14 - 1E15 /cm2. Efficiency : about 1% of the ions are incorporated and, for B and N, occupy substitutional sites, i.e. replace C-atoms. Available ions: H, B, C, N, O, F, P, S, metal ions up to W, noble gases, Ga, rare earth ions
Fluence dependent proton beam writing of 3D microstructures
Creating 3D structures for MEMS applications in p-GaAs has been recently demonstrated by our group for the first time using fluence dependent proton beam writing. Currently we are modelling the etching behavior of such proton irradiated substrated with FEM methods, using the FEM package DUNE. Application of such MEMS structures are high frequency SAW and BAW filters, energy harvesters and others.
PIXE elemental analysis with external proton beam
We operate a 3MV tandem accelerator providing MeV proton ions. A setup for external beam PIXE is available for elemental analysis of all kinds of samples. The analyzing beam is extracted through Si3N4 membranes and has a diaemeter of 1mm2. A typical analysis takes about 1-5 minutes and unes a beam current of about 5 nA. Therefore the created damage is almost negligible and the method can be considered as destruction-free.
RBS Rutherford backscattering elemental analysis
- conventional RBS with 900 keV He2+
- High resolution RBS with 450 keV He+ and 1-2 nm depth resolution
External proton beam Rutherford backscattering elemental analysis
Ion-induced self-organized surface pattern formation
Surfactant sputtering
Ion implantation physics
We use and investigate ion implantation to modify and characterize materials. The methods applied to ion implanted solids are:
- Nuclear Solid State Physics: Mössbauer spectroscoyp and Pertrubed angular correlation
- Emission Channeling and lattice location studies in semiconductors
- Perturbed angular correlation studies in oxides and sulfides
- Perturbed angular correlation studies of MAX phases
- Luminescence of Rare Earth doped Semiconductors
- Photoluminescence of wide bang gap semiconductors
- Cathodoluminescence of diamond and wide band gap semiconductors
All-digital PAC spectrometry - Digipac
You think that processing photomultiplier signals is old hat? Far form it! Our high-speed gamma-gamma angular correlation spectrometer features unprecedented data rates at high speed and excellent time resolution, which is also of potential interest to LIDAR, RADAR and other applications. Ever wanted to know how to develop multithreaded applications for digital signal processing on high-end computers and what really makes up a detector?s signal? Here you go.
Swift heavy Ion tracks in materials
The impact of single ions of high energy (1 GeV) on targets shows potential for field emitting and many other nanoscale devices based on induced ion tracks. So far only ta-C (tetrahedral amorphous carbon) shows conducting nano tracks at room temperature. Join us and accept the challenge of searching for new potential materials and applications of ion tracks such as single ion track lithography.
MASS Diodes are a new class of diodes recently invented by our group and currently investigated in detail (I-V- and C-V-characterization, FIB preparation and TEM-measurements). This type of diode, which is grown by means of mass selected ion beam deposition, features a strong rectifying behavior with high breakdown-voltages. In addition, these diodes show several unique features which makes them interesting as photodiodes/-resistors.
Wide band gap semiconductors: optical and acoustic properties
Wide band gap semiconductors are used for blue and UV light emitting devices, but also bear potential for high power, fast electronic devices frequently employed in space and military applications. Our group is involved in research of wide band gap semiconductors for more than a decade with our current focus on the optical and acoustic properties of AlN as well as BN. The picture shows a HF setup for SAW and BAW studies of AlN devices made in our lab. The behavior is modeled with large scale FEM simulations.
Rare earth based light emitters and naophosphors
Lanthanides, often denoted as rare earths, are used in solid state lasers and various light emitting devices since the 1960?s, mostly in the trivalent state Re3+. With its sharp luminescent intra-4f electron transitions they are probes of the local crystal field around the ions on their own. Our group has a capacious knowledge of the optical properties of rare earth doped systems, currently focussing on rare earth doped aluminum nitride and boron nitride in an international collaboration with American and Japanese scientists.
MAX phases
Years ago a new class of materials emerged that are nowadays called MAX phases - nanolaminated layered ternary carbides and nitrides with an unusual set of properties of both metals and high-performance ceramics. We are having a closer look at the microscopic properties of these fascinating materials under temperature and pressure variation with the use of radioactive probe nuclei.