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
Vývoj UV senzora na báze GaN pre vesmírne aplikácie
GaN-based heterostructure as a promising UV sensor for space application
Program: VEGA
Project leader: Ing. Stoklas Roman PhD.
Duration: 1.1.2019 – 31.12.2022
Vertikálny GaN MOSFET pre výkonové spínacie aplikácie
Vertical GaN MOSFET for power switching applications
Program: SRDA
Project leader: Ing. Kuzmík Ján DrSc.
Annotation: Owing the ever growing demand for the energy volume, energy attainability represents one of the most important issues of today’s society. However, there are great reserves in the energy savings available. According to available analyses, more than 10% of all electricity is ultimately lost in the form of conversion losses. Clearly, even partial improvement in the conversion efficiency can have strong economic impact. As the most of energy is now used for the electronics, corresponding scale of the losses forms at the end-user side, where the electricity is converted into a form suitable for a particular appliance. The main effort towards the conversion efficiency improvements therefore targets the area of power AC/DC and DC/DC converters for consumer and industrial electronics. Significant improvement in the conversion efficiency can be achieved by using GaN based transistors, as they are capable to operate at much higher frequencies with almost three times lower switching losses compared to Si devices.The main goal of the project is the research and development of vertical GaN MOSFET without using p-doping, and gaining the original knowledge on electrical and physical properties of the developed devices. From the quantitative point of view, our proof-of-concept device will target RON<2 mOhm/cm2 and VBD>600 V. An original feature of the proposed concept is utilization of the semi-insulating (SI) GaN as a channel layer (instead of p-type GaN), which blocks the current flow through the transistor at zero gate voltage. To open the transistor channel, positive voltage applied to the gate will be needed to induce down bend-bending in the SI GaN, allowing electron injection from the source to the drift region (along the side walls of SI GaN). This concept therefore represents a unipolar enhancement-mode transistor, while drift region is formed of un-doped GaN with extremely low density of dislocation grown directly on GaN substrate.
Duration: 1.7.2019 – 30.6.2022
Fotonické nanoštruktúry pripravené laserovou 3D litografiou pre biosenzory
Photonic nanostructures prepared by 3D laser lithography for biosensing
Program: SRDA
Project leader: doc. Ing. Novák Jozef DrSc.
Duration: 1.7.2017 – 31.12.2020
Moderné nanoštruktúry pripravené sofistikovanou MOVPE technológiou
Advanced nanostructures prepared by sophisticated MOVPE technology
Program: VEGA
Project leader: doc. Ing. Novák Jozef DrSc.
Annotation: This project is focused on the preparation of advanced nanowires and nanocones prepared by MOVPEtechnology. The main goal of the project is to study the growth and properties of GaP and GaN based nanowiresprepared by vapour-liquid-solid (VLS) technique. In addition we will concentrate our efforts on improvements andenhancement of the most recent experience obtained within previous projects. Our research will be focused intothree areas: (i) stemming from the expected application a most suitable material system will be applied (ii) themodification of the growth conditions (mainly diameter of seeds, growth temperature andV/III ratio) with the aim tomodify mechanical dimension of the nanowires (i.e. transfer from nanowires to nanocones) (iii) acquire newknowledge on the deposition of the metallic nanograins on the top of the nanocones and nanowires with aim tooptimize their properties for the SERS experiments.
Duration: 1.1.2017 – 31.12.2020
Opracovanie povrchu polovodiča ako cesta k novým III-As a III-N elektronickým súčiastkám
Surface processing of semiconductors as the way towards new III-As and III-N electronic devices
Program: VEGA
Project leader: RNDr. Gregušová Dagmar DrSc.
Annotation: Surfaces of III-V semiconductors exhibit large densisties of surface states that limit the use of the semicondutorsin electronics. Native oxides on III-V surfaces do not match the qualiy of oxides on the surface of silicon. Thesurface states have been studied and manipulated by many researchers with the aim to eliminate their infuence.Our aim is to find out how technology is used to eliminate or passivate the states. We intend to useheterostrucutres whose surface will be manipulated to allow for the preparation of high quality MOSHFETs.Manipulation with surface states leads to new types of device. It will thus be possible to integrate various types oftransistor on a single wafer. To explore properties of individual layers of heterostructure by optical measurementwill necessite their release from original substrates and transfer to host substrates. Procedures of heterostructurerelease and transfer will be used in the integration of other semiconductor devices on planar and non-planarsubstrates.
Duration: 1.1.2017 – 31.12.2020