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| ROTOLES – Optimalizovaný rast a transportné a optické vlastnosti tenkých vrstiev vybraných topologických polokovov | |
| Optimised growth and the transport and optical properties of thin layers of selected topological semimetals | |
| Program: | SRDA |
| Project leader: | Dr. rer. nat. Hulman Martin |
| Annotation: | One of the fundamental results of quantum mechanics in the 1920s was the derivation of relativistic equations formassive fermions (Dirac), massless fermions (Weyl) and fermions that are themselves antiparticles (Majorana).Since those times, particle physics has been searching for particles representing Weyl and Majorana\’s fermions.However, their search has not yet been successful.In the last twenty years, it has been shown that the band structure of some materials has such uniquecharacteristics that the charge carriers in them can behave according to the dynamics satisfying the Dirac or Weylrelativistic equations. Such materials include compounds from the group of transition metals dichalcogenides,which we will focus on in our project.We will work with very thin layers of selected materials from this group, such as PtSe2, MoTe2 and WTe2. The firststep in the implementation of the project will be the preparation of such layers by chalcogenisation of thin films oftransition metals. Their transport and optical properties will then be thoroughly investigated. Temperaturedependent transport measurements can show us transitions between different structures of the same material. We expect that a metal-insulator transition can be observed when the thickness of such thin films is varied. Some ofthese materials can go into a superconducting state at very low temperatures. We will also try to induce this state inclose proximity, i.e. when the thin layer is in contact with another superconductor.Optical measurements will be correlated with transport measurements. We derive essential frequency-dependentcharacteristics, such as optical conductivity, from the latter. We will look for characteristics theoretically predictedfor Dirac and Weyl fermions in the optical conductivity. |
| Duration: | 1.7.2024 – 30.6.2027 |
| Nanoelsen – Nanoštrukturované tenkovrstvové materiály vyznačujúce sa slabými väzbovými interakciami pre elektronické a senzorické aplikácie | |
| Nanostructured thin-film materials characterized by weak binding interactions for electronic and sensoric applications | |
| Program: | SRDA |
| Project leader: | RNDr. Gregušová Dagmar, DrSc. |
| Annotation: | The proposed project is focused on the basic research of the preparation processes and properties ofsemiconducting sulfides of transition metals such as Mo, W and Ni and selected combinations with their oxides inthe form of mixed sulfides and oxides, as well as the possibilities of their doping with noble metals (Pt, Au) for usein gas sensors as well as in supercapacitors. We also anticipate full utilization of semiconductormicroelectronic and micromechanical techniques and micro / nanotechnologies, which can significantly contributeto qualitatively improved detection properties, low operating power consumption of gas sensors as well asincreased energy efficiency and supercapacitor lifetime. |
| Duration: | 1.7.2022 – 30.6.2026 |
| Transit2D – Tranzistory na báze 2D kovových chalkogenidov pripravených teplom podporovanou konverziou | |
| Transistors based on 2D Metal Chalcogenides Grown via Thermally Assisted Conversion | |
| Program: | SRDA |
| Project leader: | Ing. Ťapajna Milan, PhD. |
| Annotation: | 2D materials can form one-atom-thick sheets with extraordinary properties. One of the most promising classes of2D materials is the transition metal dichalcogenides (TMDs). The transition from an indirect to a direct bandgap,when the bulk materials is thinned down to a monolayer, results in unique electrical and optical properties of 2DTMDs. Post-transition metal chalcogenides (PTMCs) represents another interesting group of 2D materials. Thesematerials have wide band gap and, depending on the structure of the material, show anisotropic electrical andoptical properties. The aim of this project is the fabrication of field-effect transistors with metal-oxide-semiconductorgate (MOSFETs) based on selected TMDs and PTMCs compounds and detail analysis of their transport properties.We will focus on large-area few-layer PtSe2 and GaS/GaSe films grown by thermal assisted conversion, i.e.sulfurization and selenization. Based on the existing experiences, structural, chemical and electrical properties ofhorizontally-aligned PtSe2 films prepared by selenization will be optimized, targeting mobilities similar to thoseprepared by mechanical exfoliation. Then, MOSFET technology using both, top-gate as well as bottom-gateapproach will be developed and optimized. Atomic layer deposition and metal-oxide chemical vapor deposition(MOCVD) will be employed for gate oxide growth. GaS/GaSe few-layer films will be prepared by chalcogenization |
| Duration: | 1.7.2022 – 30.6.2026 |
| Rast a optická charakterizácia 2D materiálov: MoTe2, WTe2, PtTe2 | |
| Growth and optical characterization of 2D materials: MoTe2, WTe2, PtTe2 | |
| Program: | VEGA |
| Project leader: | RNDr. Pribusová Slušná Lenka, PhD. |
| Annotation: | Research of thin-film materials noticed a significant increase, especially since the discovery of graphene, when a wide range of 2D materials began to study. A significant group of 2D materials is transition metal dichalcogenides(TMDs), including MoTe2, WTe2, and PtTe2. These materials have unique optoelectronic properties that varydue to the thickness of the layer and the crystal structure. Electrical properties vary depending on structures, fromsemiconducting to metallic. The preparation of films by tellurization of molybdenum, tungsten, and platinum ismore difficult than sulfurization or selenization due to the weaker redox properties of tellurium. The challenge in thin films is the controlled preparation of the required crystal structure of homogenous large-arealayers. This project aims to contribute to the solution of preparing these materials, characterize their structure and orientation of the films concerning the substrate, and determine the optical parameters and electrical properties. |
| Duration: | 1.1.2023 – 31.12.2025 |
| NanoMemb-RF – Moderné nanomembránové heteroštruktúry na báze GaAs pre vysoko produktívne vysokofrekvenčné prvky | |
| Advanced GaAs-based nanomembrane heterostructures for highperformance RF devices | |
| Program: | SRDA |
| Project leader: | RNDr. Gregušová Dagmar, DrSc. |
| Annotation: | The main aim of the proposed project is to expand the basic knowledge and to master the fabrication technology ofthe advanced nanomembrane AlGaAs/GaAs heterojunction devices for high-performance RF applications.Insufficient removal of the waste heat in electronic devices due to the Joule losses leading to overheating and earlydevice failure often requires foreign, high thermal conductivity substrates to be employed. As opposed to themainstream research of the GaN-based electronic devices prepared directly on sapphire or SiC, proposed GaAsbased devices will be fabricated upon self-supporting heterostructure nanomembranes transferred onto varioussubstrates. It is very timely, original, and desirable approach to extend the utilization of the GaAs-based devicesmaterial potential, as demonstrated by our preliminary results. |
| Duration: | 1.7.2022 – 30.6.2025 |
| Príprava, charakterizácia a dopovanie ultratenkých vrstiev dichalkogenidov prechodných kovov | |
| Fabrication, characterization, and doping of ultra-thin layers of transition metal dichalcogenides | |
| Program: | VEGA |
| Project leader: | Mgr. Sojková Michaela, PhD. |
| Annotation: | Thanks to the unusual physical properties, 2D materials have been intensively studied for several years. Aninteresting group of this class of materials is transition metal dichalcogenides TMD. They have a hexagonalstructure with the individual layers bonded to each other only by weak Van der Waals bonds. This causessignificantly anisotropic properties and has a significant effect on their electronic structure. Some of them showphysically interesting correlated states (superconductivity, charge density waves). The primary goal of this projectis to prepare and study the properties of thin layers of 2 different TMD – MoS2 and PtSe2, and to study theinfluence of doping with Li and Na cations on the electrical and structural properties of these layers. Thesecondary goal is to optimize growth and doping conditions to improve the parameters of thin films, such aselectrical conductivity and charge carrier mobility which will enable the preparation of functional electroniccomponents – transistors. |
| Duration: | 1.1.2021 – 31.12.2024 |
| TMD2DCOR – Metalické 2D dichalkogenidy prechodných kovov: príprava, štúdium vlastností a korelované stavy | |
| Fabrication, physics and correlated states in metallic 2D transition metal dichalcogenides | |
| Program: | SRDA |
| Project leader: | Dr. rer. nat. Hulman Martin |
| Annotation: | The discovery of graphene in 2004 has brought a massive interest of scientists active in condensed-matter physicson research of 2D materials. Even though these materials have a long history starting already in the twenties of the20th century, the past years have seen an intensive renascence of interest in 2D materials. Ultra-thin samples ofmany 2D materials have been successfully prepared with electronic properties that may exhibit correlatedelectronic phenomena such as charge density waves and superconductivity. One of the well-studied families of the2D materials are transition metal dichalcogenides (TMDs). TMDs consist of hexagonal layers of metal atomssandwiched between two layers of chalcogen atoms with a MX2 stoichiometry.In this project, we focus on those materials from the TMD family that exhibit strongly correlated electronic states:NbSe2, TiSe2, TaS2, TaSe2 and PtSe2. The goal of the project is to prepare ultrathin (≤ 10 nm) layers and bulksamples and characterise them thoroughly in terms of the thickness, crystallinity, homogeneity, optical andelectronic properties. A special attention will be paid to charge density wave states and superconductivity in thesematerials and how they evolve with the sample thickness, doping, external electric and magnetic fields and detailsof the growth process.The scientific program also aims at preparing heterostructures built up of these materials as well as hybrid systemscombining TMDs with other materials. This research also includes a detailed characterisation of heterostructures toprovide a feedback to optimise the growth process. |
| Duration: | 1.7.2020 – 30.6.2023 |