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Gli isolanti topologici sono materiali che recentemente stanno attirando molta attenzione da parte della comunità scientifica, sono caratterizzati da un bulk isolante e da delle superfici sulle quali invece sono presenti degli stati topologici 2D. Sono caratterizzati da una struttura a bande a cono di Dirac, garantendo quindi una elevata mobilità dei portatori e la presenza di una polarizzazione di spin in funzione del momento elettronico. Tale associazione fra spin e momento dei portatori si traduce nel fatto che dipendentemente dalla direzione della corrente imposta nel materiale si crea una polarizzazione superficiale. Essendo tale fenomeno invertibile (imponendo una polarizzazione superficiale si genera una corrente nel materiale) tali materiali possono essere usati come convertitori carica-spin e viceversa, garantendo in entrambi i casi un basso consumo di energia e una elevata velocità. Per questi motivi gli isolanti topologici risultano degli ottimi candidati per rendere più efficienti alcuni dispositivi presenti nell’elettronica tradizionale fra cui le memorie e le logiche. Al momento gli isolanti topologici sono cresciuti principalmente tramite MBE e tale tecnica di crescita non è compatibile con gli standard industriali, per via degli elevati costi che sarebbero necessari per supportare una produzione di massa. Risulta quindi importante ottimizzare dei processi di crescita meno costosi e compatibili con il mondo dell’industria per favorire il trasferimento di tale tecnologia nel campo della microelettronica tradizionale, come ad esempio i processi basati sulla metal-organic chemical vapor depositioin (MOCVD). In questa tesi vengono caratterizzati film sottili di Sb2Te3, Bi2Te3 e di un bilayer composto da Sb2Te3/Bi2Te3 cresciuti tramite MOCVD su wafer intrinseci di Si(111) larghi 4 ‘’. L'obiettivo è stato quello di convalidare il comportamento topologico di questi materiali cresciuti tramite MOCVD con particolare attenzione alla verifica delle loro pr, Chalcogenide thin films, such as Bi2Te3 and Sb2Te3 have been under the scientific community’s attention since long, due to their application as thermoelectric material. Recently, they are gaining additional interest because of their potential use as Topological Insulators (TIs). TIs are materials that combine the existence of insulating bulk with the presence of surfaces hosting Topological Surface States (TSS). TSS are characterized by a Dirac-like band structure with intrinsic momentum-dependent spin polarization and extremely high mobility. These features translate into the possibility of controlling the magnetization of an adjacent magnetic media by applying an electric field across the TI (charge-to-spin conversion) or vice versa (spin-to-charge conversion), in both cases with very low electrical dissipation and limited operation time. Because of these astonishing electrical properties, they have been proposed as potential materials to boost the integration of spintronic devices into ordinary electronics. However, the main currently used technique to grow TIs is Molecular Beam Epitaxy, which is not suitable to guarantee the TIs’ mass production, mainly due to the high cost to be faced when targeting wafers-scaled growth. Achieving the growth of TIs through methods allowing an easier technology transfer is therefore demanding. Among them, chemical methods are thought to be a good solution to achieve conformal TIs’ growth on large-area substrates, at a limited cost. In this thesis, I used metal-organic chemical vapor deposition (MOCVD) to optimize the growth of p-type Sb2Te3, n-type Bi2Te3, and combined Sb2Te3/Bi2Te3 bilayer, on top of Si(111) intrinsic substrate. The main focus has been to validate the topological behavior of such large-area TIs by a thorough study of their (magneto) electrical and electronic properties. In all cases, the clear existence of TSS has been demonstrated by analyzing the observed weak-antilocalization (WAL) effect and by imaging the more...

Der Bibelvers Jonah 2:1 (oft auch als Jonah 1:17 gezählt) kann so ausgelegt werden kann, dass Jonah nicht „von einem großen Fisch verschluckt“, sondern „von viel Fisch umgeben“ war, als eine Metapher fürs Ertrinken. Argumentiert wird anhand linguistischer Wortanalysen (Hebräisch, Griechisch, etc.) und der Traditionsgeschichte des Jonah-Buchs., The bible verse Jonah 2:1 (often also counted as Jonah 1:17) can be interpreted as such that Jonah was not “swallowed by a big fish”, but instead was “englufed by much fish”, as a metaphor for drowning. The argumentation is done through linguistic word-studies (Hebrew, Greek, etc.) and the historical of tradition of the Book of Jonah., vorgelegt von Christopher A. Summer, BA, MA, Dissertation Universität Innsbruck 2022 more...

Der Bibelvers Jonah 2:1 (oft auch als Jonah 1:17 gezählt) kann so ausgelegt werden kann, dass Jonah nicht „von einem großen Fisch verschluckt“, sondern „von viel Fisch umgeben“ war, als eine Metapher fürs Ertrinken. Argumentiert wird anhand linguistischer Wortanalysen (Hebräisch, Griechisch, etc.) und der Traditionsgeschichte des Jonah-Buchs., The bible verse Jonah 2:1 (often also counted as Jonah 1:17) can be interpreted as such that Jonah was not “swallowed by a big fish”, but instead was “englufed by much fish”, as a metaphor for drowning. The argumentation is done through linguistic word-studies (Hebrew, Greek, etc.) and the historical of tradition of the Book of Jonah., vorgelegt von Christopher A. Summer, BA, MA, Dissertation Universität Innsbruck 2022 more...

We study the weak antilocalization (WAL) effect in topological insulator Bi2Te3 thin films at low temperatures. The two-dimensional WAL effect associated with surface carriers is revealed in the tilted magnetic field dependence of magnetoconductance. Our data demonstrate that the observed WAL is robust against deposition of nonmagnetic Au impurities on the surface of the thin films, but it is quenched by the deposition of magnetic Fe impurities which destroy the π Berry phase of the topological surface states. The magnetoconductance data of a 5 nm Bi2Te3 film suggests that a crossover from symplectic to unitary classes is observed with the deposition of Fe impurities. more...