Our laboratory applies various techniques for thin film preparation and surface modification.
Pulsed laser deposition
Pulsed laser deposition (PLD) is a method for forming layers of inorganic materials with complex elemental compositions. After irradiation of a target with a pulsed laser in a vacuum chamber, the material is ablated, and a plasma plume is formed from the target material. The ablated material can be captured on a substrate and thereby a thin film with thickness ranging from monomolecular to tens of micrometres can be created. The physical properties can be influenced by the conditions used in the deposition process. The traditional experimental set-up includes a stainless-steel vacuum deposition chamber.
Diagram of a typical pulsed laser deposition apparatus
Radiofrequency plasma in the preparation of titanium dioxide
Two plasma plumes (carbon - top and silver - bottom)
Magnetron sputtering
DC magnetron sputtering (MS) is a deposition method using a target of conductive material that is placed in a vacuum chamber and a high negative voltage is applied to it. A working gas is introduced into the chamber and the chamber pressure is maintained in the range from tens to ones of pascals. A DC voltage is applied between the substrate and the target, igniting a glow discharge that causes ionization of the working gas atoms. Positive ions are attracted to the target and bombard it, and negative electrons are directed towards the substrate. A strong magnetic field near the target causes the electrons to move in a spiral along the magnetic field lines. The electrons strike the argon atoms on their way to the substrate and form more ions. This creates a cyclic process. As the heavy ions hit the target surface, the target is sputtered and the sputtered atoms are catapulted away from the target, where the substrate is placed in their way. The atoms on the substrate come into contact at the molecular level, bind and form a thin film.
Magnetron sputtering
Hybrid techniques
The above techniques can be combined with each other or with an additional ion source and radiofrequency discharge. This can provide unique thin films and coatings.
Combination of magnetron sputtering and pulsed laser deposition
Ion bombardment source
Equipment in our laboratory
- Two Compex 205 F excimer lasers (λ = 193/248 nm; 20 ns; E = 780 mJ/pulse; repetition rate up to 50 Hz)
- Quantel Q-SMART 850 Nd:YAG laser (λ = 1064 / 532 nm; 6 ns; E = 855 / 440 mJ/pulse; repetition rate up to 10 Hz)
- Two Torus 2" HV magnetrons (2" target; Kurt J. Lesker; MDX source – 1k)
- Kaufman-Robinson EH200F ion source with a maximum energy of 210 eV
- Radiofrequency source PFG 300 RF (TRUMPF Hüttinger GmbH)
- Ten vacuum chambers for laser and hybrid deposition with a base pressure of 10-5Pa
Laboratory for thin film preparation