Ion Beam Analysis

The interaction of high-energy ion beams with matter is a unique physical process. Using a beam of accelerated particles, it is possible not only to selectively modify various materials, but also to perform characterization of the composition of materials, including microstructures. The accelerated ions range in a material depends on their energy, so it is possible to control the parameters of the modified structure and, if necessary, implant individual isotopes of elements.

1. Equipment

1.1 Tandetron 4110A ion accelerator

Tandetron 4110A ion accelerator is a Tandem type common analytic instrument used for ion implantation, ion backscattering, PIXE (particle induced x-ray emission) and other analytical techniques.

The negative ions of the required element are selected using an injection magnet, then focused and directed to the acceleration system with a constant voltage generator, which can operate at up to 1 MV. The acceleration system consists of a voltage divider, corona rings, a gas stripper terminal, focusing elements, and a 1 MV power supply. In the acceleration system, negative ions are accelerated (up to 1 MV) using the positive potential of the voltage terminal. The voltage terminal contains a gas ion charge exchange cell, where negative ions lose electrons and are converted into positive ions. The positive particles are then pushed towards the grounded output of the acceleration system by the positive 1 MV potential. The energy of the accelerated ions at the output depends on the ion charge state and can reach up to 2.0 MeV for singly ionized particles and up to 5.0 MeV for quadruply ionized particles.

1.2 Hiconex 834 negative ion source

Hiconex 834 is a heavy ion source producing microampere intensity negative ion beams from a wide variety of elemental materials as well as complex compounds. It is used not only as a injection source for the Tandetron 4110A ion accelerator, but also as a stand-alone source providing various types of ions at energies from 10keV to 30keV for the ion implantation.

2. Performed research

2.1 Ion implantation

High energy ion injection might imply formation of new material not in thermodynamic equilibrium bypassing normal chemical solubility rules. That provides a possibility to achieve defects just in desired place of the sample and at levels, which are inaccessible by conventional treatment.

Therefore, implantation process might be performed to tune properties  of complex materials (e.g., nanostructures) or devices locally and at desired depth after their synthesis is finished. The control of created defect introduction and their evolution during implantation performed by in situ measurements.

1. a) Implantation of various positiveions with energy from 0.7 to 5 MeV using ion accelerator, e.g.:

• H⁺, C⁺, S⁺N⁺, Si⁺, O⁺, Mg⁺, Zn⁺, Cu⁺, Ge⁺, Ga⁺, As⁺, etc. up to 70 mikrometer depth depending on the type of target material and ion energy;
• Implantation of different charge state ion species, e.g.: C⁺C²⁺ C³⁺ C⁴⁺.

1. b) Implantation of negative ions with energy up to 30 MeV using ion source Hiconex, e.g.:

• Various negative ion species - H^-, C^-, S^-N^-, Si^-, O^-, Mg^-, Zn^-, Cu^-, Ge^-, Ga^-, As^- , etc.
• Molecular (polyatomic) beams: Al^-, Al₂^-.

1. c) Ion implantation optimization according to the following post-impantation processes peculiarities for the creation and following implementation of new technologies for materials and their complex structures modification, e.g.:

• Theoretical simulation of implantation process before experiment;
• decreasing ion implantation current up to pA increasing implantation time and vice versa – shortened implantation time with relatively higher ion fluence;
• using implantation of several ions at various depth to the same target;
• using different energy for the same ion species (contact formation process), etc.

1. d) Possible correction of carriers lifetime in the particular depth of the completely formed semiconductor structures.

2.2 Material analysis 

5. a) Particular matters quantitative (relative units %, ‰)  and qualitative (abs units using NIST and other standards) concentration measurements using Particle induced x-ray emission (PIXE) method for elements heavier that Mg.
   Canberra 7905-BWR bellows-sealed windowless retractable cryostat is used for PIXE experiments. It has lithium-drifted silicon 30 mm²active area, detector resolution (FWHM) is 165 eV at 5.894 keV for ⁵⁵Fe X-ray peak.
6. b) Chemical elements concentration profiling up to 30um depth using Rutherford backscatering specroscopy  (RBS) method.

ORTEC CR-015-050-100 is used for backscattering experiments. It has 15 keV alpha resolution (FWHM) at 5.486 MeV energy and 50 mm² active area.

1. c) Stechiometric and impurities measurements in oxide and other layers using combined RBS and PIXE method.
2. d) Quantiative analysis of heavy metals in aerozol filters using PIXE method.
3. e) Ion induced liuminescence measurements during ion irradiation.

2.3 Various types of test for research and cosmos technologies 

1. a) Irradiation of electronics, optics, avionics systems or their parts using protons up to 2MeV and heavier ions up to 5MeV.
2. b) Materials or parts degassing process in vacuum dynamics and characterization.
3. c) Various types of experiments in vaccum chamber with sample cooling/heating and power/signal cable inlet capabilities for test of various prototypes .
4. d) Materials irradiation in athmospheric conditions using proton beam.

2.4 Design, service and repair of low (100kPa-3.3kPa), middle (3.3kPa-130mPa), high (130mPa-130µPa) iand super-high (130µPa-130nPa) vacuum systems.

2.5 Design and service of  various gas supply and pneumatic control systems.

Contact person:

Dr Vitalij Kovalevskij

vitalij.kovalevskij@ftmc.lt