We present a novel technique to fabricate single-electron transistors (SETs) with silicon quantum dots (QDs) as
conducting islands making use of a combination of self-assembly and self-alignment effects (for an overview of the
fabrication process, see Fig. 1). Starting from an ultra-thin silicon-on-insulator (SOI) substrate we employ aminosilane
molecules as an adhesion agent to self-assemble gold colloidal particles in a sub-monolayer [1]. These particles are then
used as an etch mask for a CF₄ reactive ion etch (RIE) process in which the silicon layer is removed everywhere except
below the gold colloids, yielding silicon QDs on a SiO₂ insulating layer. A metal wire together with symmetric side gate
electrodes is patterned by electron beam lithography (EBL) onto the QD-covered sample, and a nanometer-sized gap is
created in these wires by a controlled electromigration process [2]. Self-alignment of the evolving nano-electrodes with
respect to the QDs is achieved, because the metal layer is locally dilated by the QDs resulting in a locally higher current
density. Therefore the metal wires will preferentially break at the positions of the QDs. To obtain tunneling contacts the
native oxide layer covering the silicon QDs is used as a tunneling barrier. Its thickness can be adjusted in a controlled
manner by self-limiting thermal oxidation [3] to obtain an accurate tunneling resistance.
The devices are electrically characterized at liquid helium temperature by applying a source-drain voltage and
measuring the current. The I(V)-curves (Fig. 2) show clear Coulomb blockade behavior and Coulomb staircase features.
When the source-drain voltage is kept at a constant value and the gate voltage is varied, conductance oscillations
become visible. By collecting I_SD(V_SD)-traces for different gate voltages and calculating their numerical derivatives a so-
called stability diagram is obtained, exhibiting Coulomb diamonds which are typical for SETs.

We present a technique to contact individual silicon quantum dots (QDs) by nano-­electrodes making use of a self-­alignment effect. Starting from an ultra thin silicon on insulator (SOI) substrate we employ self­-assembled gold colloidal particles as an etch mask. These particles are deposited onto the substrate using aminosilane [3­-(2­-aminoethylamino)propyltrimethoxysilane] as an adhesion agent yielding a sub­-monolayer sample coverage. The QDs are then fabricated by applying a CF₄ reactive ion etch (RIE) process to remove the silicon layer everywhere except below the gold colloids. Subsequently, the colloidal mask is removed by a wet chemical etch and 100-200 nm wide metal wires are patterned by electron beam lithography (EBL) onto the QD-­covered samples. A nanometer­-sized gap is created in these wires by a controlled electromigration process. The metal wires will preferentially break at the positions of the QDs, because the metal layer is dilated there resulting in a locally higher current density. This leads to a self­-alignment effect of the evolving nano­-electrodes with respect to the QDs. The native oxide of the silicon QDs is used as a tunneling barrier leading to a single­-electron device. The oxide thickness can be increased in a controlled manner by self­-limiting thermal oxidation to adjust the tunneling resistance. Finally, I(V)­-traces of these devices are collected at liquid helium temperature. They show clear Coulomb blockade behavior as well as Coulomb staircase features.

In this paper we present a novel approach to fabricate single-electron devices utilizing different self-organization and self-alignment effects. Silicon quantum dots (QDs) are obtained employing reactive ion etching (RIE) into a silicon-on-insulator (SOI) substrate with a self-assembled etch mask. Electrodes with nanometer separation are fabricated and aligned to the QDs by means of a controlled electromigration process. The tunneling rates of the devices are defined by the native oxide covering the silicon QDs and can be adjusted by self-limiting thermal oxidation. The devices show clear Coulomb blockade behavior as well as Coulomb staircase features. In some samples also a gate influence is present giving rise to Coulomb diamonds in the differential conductance diagram.

Le chiese costituiscono un patrimonio inestimabile di oggetti sacri e di culto, reliquie, opere d’arte, organi, costruzioni monumentali, arredi, decorazioni, non inferiore a quello contenuto in musei e palazzi storici. Questo patrimonio che in seguito viene indicato con il termine beni culturali, va preservato da costanti ingiurie ambientali. I beni culturali sono sensibili alla temperatura e all’umidità relativa e negli anni si sono adattati al particolare microclima locale, ai suoi valori medi e alla sua variabilità. Molte chiese, rimaste per secoli al freddo, ci hanno tramandato numerosissime opere in buone condizioni, ma negli ultimi decenni, dopo che ha preso piede l’uso del riscaldamento, il loro stato di conservazione ha subito un pesante contraccolpo. Sono possibili due strategie di riscaldamento delle chiese: 1) riscaldare l’ambiente destinato ad accogliere le persone (riscaldamento generale); 2) lasciare l’ambiente freddo e cercare di riscaldare solo le persone (riscaldamento localizzato). Il riscaldamento generale ha il vantaggio di utilizzare tecniche tradizionali, ben note; comporta però un grande spreco energetico, ma soprattutto un alto rischio di provocare danni alle opere. Nel riscaldamento localizzato, invece l’utilizzo mirato del calore consente una ridotta dispersione e quindi un basso costo energetico, e soprattutto offre ai manufatti condizioni microclimatiche imperturbate, senza rischi per la conservazione. L’oggetto della presente guida è fornire un supporto scientifico per la scelta e l’uso del sistema di riscaldamento e per ridurre al minimo le conseguenze negative ai fini della conservazione. Il problema nella sua complessità è enorme, date la quantità, la qualità, la varietà e la delicatezza dei manufatti presenti nelle chiese. Questa guida non ha l’ambizione di chiarire tutti gli aspetti della questione, ma cerca semplicemente di far capire a quali rischi per i beni culturali possa portare un sistema di riscaldamento, suggerendo che questi rischi vergano sempre affrontati e discussi da esperti nelle varie problematiche coinvolte.