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In-situ X-ray Characterization Group - Pulsed Laser Deposition of Thin Films

Research

Motivation

In-situ RHEED was being used as a diagnostic tool to control the growth and surface morphology of thin films. The quality of film surface in term of roughness would influence the RHEED pattern and therefore, the growth mode as well as growth rate could be determined.

In-situ X-ray diffraction under wide and grazing incidence angles methods represent powerful tools to online monitor the surface as well as the bulk of the grown film. It enables to follow during the growth the evolution of the strain and strain relaxation. Furthermore, defect like threading dislocation and stacking faults could be accurately determined as function of the growth parameters such as oxygen pressure, laser fluence and substrate temperature etc…The mission of the research group is to understand the PLD growth of oxide thin films by performing time resolved X-ray investigation within 1s acquisition time using fast read out sing photon counting detector 1D and 2D available at the synchrotron. Our goal would be the establishment of relationship between structure and measurable physical properties such as dielectric, magnetic, ferrormagnetic and ferroelectric properties in collaboration with other partners. The in-situ PLD growth analysis will cover diverse scope of materials which includes versatile applications as follow:

  • Defect formation dependency on growth parameter for dielectric oxide materials like Ba0.5Sr0.5TiO3   grown on MgO for microwave applications.
  • Detection of the domain formation during the growth and determination of the corresponding critical film thickness inducing this phenomenon.
  • Study of the crystal structure and defect changes during the annealing and the cooling processes using in-situ X-ray characterization methods.
  • Strain engineering of ferromagnetic films such as La0.67Sr0.33MnO grown on 3 different type of substrate like SrTiO3, LSAT and NGO.
  • Study in the Ferroelectric-Ferromagnetic FE-FM coupling in multiferroic material (example La0.67Sr0.33MnO3/BiFeO3 grown on different substrates).

 


Current project

A collaborative project is established between the synchrotron facility ANKA, Institute of Micro Technology IMT and the Institute for Data Processing and Electronics (IPE) to understand the role of growth parameter on the morphology and structure and how these latter would influence the microwaves properties. The goal is to tailor the capacitance and loss factor by optimizing the growth parameter such as oxygen pressure, laser fluence and substrate temperature. Complementary studies about the crystal structure and quality and surface morphology will be provided through a combination of several investigations methods performed in collaboration partners at IMT and INT and at the synchrotron facility ANKA. Ex-situ X-ray characterization using diffractions method in the coplanar and in the non-coplanar geometries (Grazing Incidence Diffraction GID) will devoted in the analysis and determination of the strain and strain relaxation and the defect formation. The goal is to understand the influence of the growth parameters on the structural features and therefore on the microwaves properties. Using the laser writer method, the device is fabricated at the institute of Micro technology after growing them at PLD chamber at ANKA. The microwaves properties of of Interdigital capacitor device IDC device in term of capacitance and loss factor will be measured at the Institute for Data Processing and Electronics as function of the frequency up to 20 GHz.

Insitua Characterization ANKA

In-situ PLD-diffractometer system at the NANO beamline

We have recently developed a PLD chamber dedicated at the NANO beamline for in-situ structural characterization during the growth process using in-situ high resolution X-ray diffraction and in-situ surface scattering methods.

The essential features of this sophisticated PLD chamber are:

  • Ability to perform correlated investigations involving in-situ X-ray synchrotron and in-situ RHEED studies with the goal to understand the influence of growth parameters on the growth mode and on the final structure of (epitaxial) thin films.
  • The laser beam with the different available wavelengths 1064, 532, and 266 nm could be focused onto the target with a motorized focus lens via a motorized mirror.
  • Automatic change of the lens position and mirror angle with the substrate-target distance to maintain a constant fluence and beam position on the target.
  • Availability of eight different targets for sequential heteroepitaxy of diverse multilayer and superlattice structures.
  • Equipped with a differentially pumped RHEED gun operational up to 30 kV and a RHEED screen for imaging the electrons from the RHEED gun diffracted on the sample surface.
  • Adjustable distance from 35 mm to 100 mm  between the target and the substrate
  • The manipulator supports the target rotation and a sideways toggling motion for even targets
  • The load lock chamber holds a sample storage rack that can hold up to six samples.
     


PLD growth chamber from the beam exit Beryllium  window.
The chamber was designed to be coupled to the heavy duty diffractometer, which features two different detection systems such as a single photon counting linear detector Mythen 1K as well as a two-dimensional pixel detector Pilatus 100K from the company Dectris in Switzerland. The possibility to swap between these two detection systems ensures in future investigations with an efficient use of the beam time as it is fast enough to successively record 2D-RSMs and 3D-RSMs during the growth process.
Our in-situ X-ray diffraction PLD chamber contains high purity beryllium windows allowing for X-ray transmission. The entrance beryllium window has a horizontal angular opening of 55°, whiles the exit beryllium window built in L-shape, has vertical and horizontal openings of 55° and 70°, respectively.

 

 

Dr. Sondes Bauer

baue

Head of the scattering group and leader of in-situ PLD research group

Sondes.bauer∂kit edu

Physics and materials science with synchrotron radiation, nanoscience, time resolved structure investigation, In-situ high resolution diffraction investigation of thin films and nanostructured materials, In situ chemical mapping of a lithium-ion battery using full-field hard X-ray spectroscopic imaging

 

 

 


Dr Adriana Rodriguez

Dr Adriana Rodriguez

Postdoc at the synchrotron Facility ANKA since December 2014

adriana.rodrigues∂partner.kit edu

Growth PLD of transition metal oxide films like Ba

Morphology and crystal characterization using synchrotron diffraction, atomic force microscopy and X-ray photon spectroscopy methods

 


Talks

Teaching

Collaborations

Open Positions

If you are interested in a Bachelor/Master or Diploma thesis in the field of surface science and/or modern synchrotron radiation methods, contact us. Examples of currently offered topics are given below.

 

 

Diploma, Bachelor or Master Thesis:

In-situ X ray characterization of Multiferroics oxide thin Films during Pulsed Laser Deposition at the Nano Beamline of the National Synchrotron Facility ANKA

Job description: Multiferroics are attracting increasing interest, the coexistence and coupling of ferroelectric and magnetic orders has made them as potential candidate for novel multifunctional devices such as sensors, transducers, memories and spintronics. Multiferroic magnetoelectric (ME) composite systems, such as ferromagnetic–ferroelectric heterostructures offer a novel route for integrating ferroelectric and ferromagnetism. The candidate shall perform growth studies of Multiferroic magnetoelectric (ME) composite systems with the new PLD chamber with the unique feature, that it can be integrated into the NANO beamline at the ANKA synchrotron facility. The candidate shall perform In-situ X-ray characterization during pulsed laser deposition (In-Situ PLD) combined with high pressure RHEED to study the time evolution of the crystal structures and the microstructure of the oxide thin films, (e.g. the domain size and the distribution of crystalline orientation) at the growth temperature, during the film formation. The main focus will be given to the study of the PLD growth and properties of bilayers of the La2/3Sr1/3MnO3 (LSMO) half-metal combined with BiFeO3 and epitaxial grown onto SrTiO3 (001) and other type of substrates with different type of miscut. The candidate will perform systematic experimental investigation of the influence of the growth parameters like annealing temperature, gas pressure, pre and post-treatment on the microstructure, strain, the defect density and interface quality of the grown thin films. One goal is to detect the critical thickness of morphology instabilities.

Qualification:
Candidates should be student in physics and speaking fluently English (good level in reading and writing). Strong interests in experimental solid state physics, surface science/nanotechnology, and/or crystallography is required. Programming skills, in Matlab, C, C++, and/or Python, are advantageous.

Salary:
Remuneration shall be based on the Collective Agreement for the Public Service Sector.

Institute/Department:
ANKA Synchrotronstrahlungsquelle

Contract duration:
limited 4-6 months after study regulations

Starting date: By appointment

Contact person in line-management: Dr. Sondes Bauer

Contact

If you would like to know more about our activities or you are interested in collaboration do not hesitate to contact us.

Dr. Sondes Bauer

Scattering group leader

Karlsruhe Institute of Technology (KIT)

Institute for photon Science/Synchrotron Facility ANKA
Hermann-von-Helmholtz-Platz 1
Building 329
76344 Eggenstein-Leopoldshafen, Germany

Phone: +49 721 608 26489
Email: Sondes.Bauer∂kit.edu