Rita Rizzoli

Charge transport in graphene–polythiophene blends as studied by Kelvin Probe Force Microscopy and transistor characterization

Blends of reduced graphene oxide (RGO) and poly(3-hexylthiophene) (P3HT) are used as the active layer of field-effect transistors (FETs). By using sequential deposition of the two components, the density of RGO sheets can be tuned linearly, thereby modulating their contribution to the charge transport in the transistors, and the onset of charge percolation. The surface potential of RGO, P3HT and source–drain contacts is measured on the nanometric scale with Kelvin Probe Force Microscopy (KPFM), and correlated with the macroscopic performance of the FETs. KPFM is also used to monitor the potential decay along the channel in the working FETs.

Graphene-epoxy flexible transparent capacitor obtained by graphene-polymer transfer and UV-induced bonding.

A new approach is reported for the preparation of a graphene-epoxy flexible transparent capacitor obtained by graphene-polymer transfer and UV-induced bonding. SU8 resin is employed for realizing a well-adherent, transparent, and flexible supporting layer. The achieved transparent graphene/SU8 membrane presents two distinct surfaces: one homogeneous conductive surface containing a graphene layer and one dielectric surface typical of the epoxy polymer. Two graphene/SU8 layers are bonded together by using an epoxy photocurable formulation based on epoxy resin. The obtained material showed a stable and clear capacitive behavior.

Graphene-lipids interaction: Towards the fabrication of a novel sensor for biomedical uses

In this work we investigate the use of graphene as transducer in a novel biosensor for biomedical uses, in which electroactive membrane proteins would serve as biological recognition elements. Membrane proteins maintain their functionalities only if embedded in the cell membrane, so it is necessary to develop a system, which mimics their native environment. This study is focused on surface treatments of graphene to improve its biocompatibility and a first investigation of its interaction with liposomes, which rupture and spread to form a Supported Lipid Bilayer under specific surface conditions. The first step involved the characterization of the graphene membranes synthesized by Chemical Vapor Deposition, using several techniques to determine their morphological and structural properties. From these investigations, the CVD-synthesized graphene resulted to be mono- to few-layer. Next, the interaction of graphene with lipids (1,2-dioleoyl-sn-glicero-3-phosphocholine), in particular the formation of a supported lipid bilayer due to the liposome spreading, was investigated via electrochemical impedance spectroscopy. This indicated the presence of a stable insulating lipid layer on the graphene surface after liposome incubation.

Carbon-Cap for Ohmic Contacts on n-Type Ion Implanted 4H-SiC

In this study a pyrolyzed photoresist film that has been used for protecting the implanted surface of a 4H-SiC wafer during post implantation annealing at 1800-1950 °C has preserved on the wafer surface and used for the fabrication of ohmic contact pads on P+ implanted areas. The carbon film has been patterned by using a RIE O2-based plasma. A specific contact resistance of 9  10 5 cm2 has been obtained on P+ 1  1020 cm 3 implanted 4H-SiC. Micro-Raman characterizations show that the carbon cap is formed of a nano-crystalline graphitic phase.

Carbon nanotubes grown by catalytic CVD on silicon based substrates for electronics applications

To exploit the impressive electronic, mechanical and thermal properties of Carbon Nanotubes (CNTs) in the nanoelectronics technology, the development of deposition methods enabling the synthesis of well ordered, properly located and reproducible CNTs structures, is strongly recommended. We have been developing catalytic CVD synthesis of CNTs in order to get aligned nanotubes for applications ranging from nuclear particle-position detectors and cold cathode emitters for storage devices, to interconnects, vias and CNT-FETs. In this paper, the significant achievements gained on CVD growth processes for the CNTs deposition are presented. Ni and Fe catalyst nanoparticles have been obtained starting from thin films evaporated on silicon based substrates. The growth of vertically aligned carpets of MWNTs and horizontally aligned SWNTs, having a diameter of about 1 nm and bridging between patterned catalyst islands, has been accomplished. The SEM, TEM, Raman spectroscopy and AFM characterizations are discussed.