Research of materials suitable for modern electronics and sensors at IEE SAS

Materials such as oxide layers represent a modern trend in the development of superconducting structures. Current areas of research include the study of oxide layers, either directly dielectric layers or metal oxide layers, where great attention is paid to the preparation and properties of layers and structures with a perovskite structure.

For the realization of final applications, such as bolometric detectors using perovskite materials, however, remain open questions. Perovskite thin films and structures suitable for modern electronics and sensors are linked to the VEGA project in which scientists from the Institute of Electrical Engineering SAS studied ferromagnetic La_0.67Sr_0.33MnO₃ (LSMO) layers for the development of a bolometric sensor operating at room temperature in the THz frequency range. For thin films of this material, it was possible to observe a resistive and at the same time a ferromagnetic transition at a temperature above 300 K.

“Microbolometers produced by our colleagues do not require any cooling and can be made from eg. portable sensors for poisonous gases, ”says RNDr. Marianna Španková, PhD.

 

 

Schematic cross-section of a circular membrane containing the LSMO microbolometer structure. From the back side, the substrate is depleted into the membrane by dry etching (Selective DRIE).

 

The implementation of such a sensor realized on a silicon substrate requires the growth of high-quality separation layers [yttria-stabilized ZrO₂ (YSZ), CeO₂, Bi₄Ti₃O₁₂ (BTO)] of the required parameters.

“In the project, we focus on modifying the Si / dielectric layer interface to reduce the formation of an undesirable amorphous SiO₂ layer on the surface of the Si substrate. We are looking for other ways to realize this reduction using other materials such as SrO, resp. TiN. Their use could mean a simplification of the separating layer system for the deposition of the final LSMO on silicon, which could be directly applied e.g. SrTiO₃ layer followed by the final LSMO layer. Such analysis and study will, in general, be of great importance also for other systems of Perovskite structures. The question is to find out whether the alternatives offered will provide better structural properties of the final epitaxial layers. The open question in the preparation of bolometric structures is the behavior of the BTO layer. ”

The literature published so far and personal consultations show that the growth of BTO layers is, according to the responsible investigator, quite unrepeatable.

“A smooth epitaxial surface is often observed, but grains are also rotated perpendicular to the mat, and sometimes the structure breaks down completely. It is a general effort to overcome this problem, which requires a further detailed study of BTO layer growth. ”

 

 

Different surface morphology of LSMO layers applied to the same substrate.

 

Slovak researchers are working closely with the Institute of Physics of the Polish Academy of Sciences on the preparation of thin films.

RNDr. Marianna Spankova, PhD. see the benefits of the project in realizing and optimizing layers of different types with an emphasis on optimizing the Si interface / separating layer using a pulsed laser deposition device for layer deposition.

“We will gain new insights into the growth and structure of the BTO layer, respectively its replacement with another suitable layer (TiO₂ / SrTiO₃ system), ”she concluded.

 

Information and illustrations provided by: RNDr. Marianna Španková, PhD., Institute of Electrical Engineering SAS

Prepared by: Slávka Cigáňová (Habrmanová), NCP VaT at CVTI SR

Illustrative photo: Pixabay.com / artbaggage /

Source: https://vedanadosah.cvtisr.sk/

Posted by: MS