Thesis supervisor: Miklós Fried
Location of studies (in Hungarian): Obuda Univerity Abbreviation of location of studies: ÓE
Description of the research topic:
The physical, chemical and structural properties of the cutting-edge materials are strongly dependent on their composition. The common procedure to reveal the properties of concentration dependent phases is the preparation of numerous two (or more)-component samples, one for each CA/CB=1-A composition, and the investigation of these individuals. This is a low efficiency procedure that costs enormous time of man and machine. Contrarily, using the combinatorial material synthesis approach, materials libraries can be produced in one experiment that contain up to several hundreds or thousands of samples on a single substrate. In order to identify optimized material structures in an efficient way, adequate automated micro-spot material characterization tools have to be applied. The preparation devices (DC magnetron, pulsed mode reactive DC magnetron and biased RF sputtering systems as well as laser ablation deposition system) and characterization instruments (Spectroscopic Ellipsometry - SE, Rutherford Backscattering Spectrometry - RBS, Transmission Electron Microscopy - TEM, Scanning Electron Microscopy - SEM, Atomic Force Microscopy - AFM) which can be used in MFA offer powerful tools for the fabrication and processing of materials libraries as well as for accelerated material characterization on appropriate planar substrates such as Si or oxidized Si wafers. These methods can help to search more efficient advanced functional materials for micro- and optoelectronics, energy converters (solar cells) or different (optical or gas) sensor systems.
Materials to be studied
Control of the optical properties of the SiOxNy and AlOxNy layers for low-loss, high-index contrast optical waveguides which is an important task in integrated optics. To improve the control of the optical properties of the SiOxNy and AlOxNy layers we plan to use bias and/or pulsed sputtering technology.
Metal-oxide mixed thin films for efficient gas sensors and electro-chromic devices
Metal oxide films are beneficial for solid state gas sensors. There is a need to improve the sensor signal, selectivity, stability and the rate of sensor response by optimizing the chemical, structural, bulk and surface properties of applied metal oxides.
In the frame of this proposal, we aim to understand the electrochromic behavior of mixed Metal oxides deposited by reactive sputtering. We will prepare different thin films of mixed Metal Oxide by reactive DC magnetron sputtering. The deposited films will be characterized by a variety of methods
Preparation method
A one-sample concept micro-combinatorial method [G. Sáfrán: “One-sample concept” micro-combinatory for high throughput TEM of binary films” Ultramicroscopy 187 (2018) 50–55] has been developed, that eliminates the incompleteness of the previous combinatorial solutions. Its main advantages are that a single gradient sample contains the whole library of a binary system and the sample size can be adjusted according to the demands of the analytical technique.
Characterization methods
Spectroscopic Ellipsometry (SE http://www.ellipsometry.hu/)
Woollam M-2000DI rotating compensator spectroscopic ellipsometer. Wavelength range of 191-1690 nm (photon energies of 0.7-6.5 eV), Automatic scan with a micro-focused (ca. 0.2 mm) spot. Angle of incidence: 45-75 degree. Measurement time 1 sec per spot. High-resolution, high-accuracy map over 15x15 cm area within a reasonable time.
For big area (30x30 cm samples) our home-made new mapping technique will be used. Non-collimated (non-parallel, mostly diffuse) illumination with an angle of incidence sensitive pinhole camera detector system and it works as an unusual kind of imaging spectroscopic ellipsometer. (http://www.ellipsometry.hu/)
Ion Beam Analysis (IBA): Rutherford Back Scattering (RBS) (http://mffo.rmki.kfki.hu/EG2R)
Rutherford backscattering spectrometry (RBS) analysis can be performed in a scattering chamber (vacuum: 10-4 Pa) with a two-axis goniometer connected to the 5 MV EG-2R Van de Graaff accelerator of the Wigner RMI Institute of the Hungarian Academy of Sciences. He+ ions with analysing energy: 0.6-3.5 MeV. Beam spot size: 0.50.5 mm2, beam divergence: below 0.06o. Mapping area: 10x10 cm with 0.5 mm resolution. The composition can be measured in a wide range of atomic masses, e.g., we can analyse C, O, Si, Al, Mg, Mn, Fe, Ge, etc. The measured data will be evaluated with the RBX spectrum simulation code.
TEM (http://www.thinfilms.hu/grouphrem.html)
- PHILIPS CM 20 (200kV) TEM equipped with EDS for conventional TEM studies
- JEOL 3010 (300kV) HRTEM (0.17nm point resolution) equipped with a GATAN TRIDIEM EELS
SEM (http://www.mems.hu/facilities)
-scanning electron microscopy (SEM) LEO 1540 XB with cca. 10nm resolution with EDS element analysis.
Electrical properties and gas sensing evaluation (http://www.mems.hu/competencies)
- Instrument for 4-point van der Paw electrical measurements in controlled gas-chamber
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