Search results for "molekyylielektroniikka"
showing 6 items of 6 documents
Control of Molecular Orbital Ordering Using a van der Waals Monolayer Ferroelectric
2022
Two-dimensional (2D) ferroelectric materials provide a promising platform for the electrical control of quantum states. In particular, due to their 2D nature, they are suitable for influencing the quantum states of deposited molecules via the proximity effect. Here, we report electrically controllable molecular states in phthalocyanine molecules adsorbed on monolayer ferroelectric material SnTe. In particular, we demonstrate that the strain and ferroelectric order in SnTe creates a transition between two distinct orbital orders in the adsorbed phthalocyanine molecules. By controlling the polarization of the ferroelectric domain using scanning tunneling microscopy (STM), we have successfully…
DNA-molekyylin sähkönjohtavuusmittaukset
2012
DNA-molekyylien sähkönjohtavuus on askarruttanut tutkijoita jo usean vuosikymmenen ajan. Periaatteessa DNA-molekyylin sähköiset mittaukset eivät eroa mitenkään minkä tahansa sähkökomponenttien mittauksesta. Useat tutkimukset ovat kuitenkin osoittaneet, että hyvin monet parametrit mittausjärjestelyissä vaikuttavat saatuihin tuloksiin merkittävästi, joten mitään yksiselitteistä vastausta DNA:n sähkönjohtavuuteen ei ole saatu. Tämä opinnäyte keskittyykin näissä erityyppisissä mittauksissa käytettyjen mittausjärjestelyjen tarkasteluun ja saatuihin tuloksiin. Tutkimukset jaotellaan epäsuoriin ja suoriin mittauksiin, joiden erityispiirteet pyritään selvittämään. Lisäksi mittausten tuloksia pyritä…
Many-particle theory for time-dependent quantum transport in nanostructures
2012
During the recent decades, molecular electronics has established its place as one of the promising fields in the nanoscience. The possibility to manufacture and control molecular junctions where single molecules are squeezed between the conducing electrodes has opened up new possibilities to develop nanoscale devices which could be employed as building blocks for future nanoelectronic applications. The driving force for this new branch of physics has been the experimental advances but also theoretical methods have been under intensive study and many theoretical tools have been developed to understand the electron transport processes in the nanoscale systems. This thesis focuses on developin…
Developments in many-body theory of quantum transport and spectroscopy with non-equilibrium Green's functions and time-dependent density functional t…
2015
The problem of quantum dynamics in open systems has gained attention in recent decades and not the least due to the advances made in quantum transport in molecular systems. The main motivation behind quantum transport and molecular electronics is the futuristic goal to be able at some point to replace, or to complement, the silicon-based technology and to make the electronic devices faster. On a fundamental level, one has to deal with time-dependent processes where electron-electron or electron- phonon interactions are of great importance, and they can cause profound quantitative and qualitative changes on the physical and dynamical properties of electronic systems compared to the non-inter…
Metal-nanoparticle-G4-DNA conjugates and their DC conductivity measurements
2013
Due to superior self-assembly properties, DNA is a very promising candidate for the basis of future bottom-up solutions for molecular electronics and therefore the conductivity of DNA is a very crucial question. In this work DC conductivity measurements on conjugates consisting of G-quadruplex DNA and metal nanoparticles were carried out. The fabrication and results obtained from the electrical measurements of three types of conjugates (20nm G4-AgNP chains, 20nm G4-AuNP flowers and 60nm G4-AuNPs) are reported. Additionally, 20nm AuNP chains coated with G4 were fabricated but not measured electrically. Results reported here indicate that in ambient conditions G4-DNA exhibits insulating behav…
Conductivity measurements of DNA TX tile and origami structures
2011
Tässä tutkielmassa on tutkittu kahden erilaisen itsejärjestyvän DNA-rakenteen sähkönjohtavuutta nanomittakaavassa. Ensimmäinen rakenteista on suorakaiteenmuotoinen kaksiulotteinen DNA-levy kooltaan noin 70×100 nm2 toisen ollessa selvästi kapeampi, noin 10×60 nm2. Suurin ero rakenteiden välillä on valmistusmenetelmä: isompi rakenne on valmistettu origamitekniikalla ja pienempi niin sanottua tiilimenetelmää käyttäen. Molekyylielektroniikan kannalta DNA:n sähkönjohtavuus on oleellinen asia, sillä DNA on itsejärjestäytymisominaisuuksiensa vuoksi osoittautunut hyvin lupaavaksi molekyyliksi: yksinkertaisten nanoskaalan laitteiden valmistus käyttäen DNA-pohjaisia menetelmiä on jo mahdollista. Työs…