Giorgio Signorello

IBM · Binnig and Rohrer Nanotechnology Center

III-V compound semiconductors are indispensable materials for today's high-end electronic and optoelectronic devices, and are being explored for next-generation transistor logic and quantum technologies. III-V surfaces and interfaces play the leading role in determining device performance and, therefore, methods to control their electronic properti...

We present an automatic measurement platform that enables the characterization of nanodevices by electrical transport and optical spectroscopy as a function of uniaxial stress. We provide insights into and detailed descriptions of the mechanical device, the substrate design and fabrication, and the instrument control software, which is provided und...

Many efficient light-emitting devices and photodetectors are based on semiconductors with, respectively, a direct or indirect bandgap configuration. The less known pseudodirect bandgap configuration can be found in wurtzite (WZ) semiconductors: here electron and hole wave-functions overlap strongly but optical transitions between these states are i...

We report CMOS-compatible integration of compound semiconductors on Si substrates. InAs and GaAs nanowires are selectively grown in vertical SiO2 nanotube templates fabricated on Si substrates of varying crystallographic orientations, including nano-crystalline Si. The nanowires investigated are epitaxially grown, single-crystalline, free from thre...

The monolithic integration of III-V nanowires on silicon by direct epitaxial growth enables new possibilities for the design and fabrication of electronic as well as optoelectronic devices. We demonstrate a new growth technique to directly integrate III-V semiconducting nanowires on silicon using selective area epitaxy within a nanotube template. T...

We report on the growth, structural and electrical characterizations of Be-doped GaAs nanowires (NWs) grown by the Au- and Ga-assisted vapour-liquid-solid techniques using molecular beam epitaxy. The growth rate of Be-doped GaAs NWs grown by the Au-assisted technique is observed to be lower as compared to the growth rate of undoped GaAs NWs grown u...

Strain engineering has been used to increase the charge carrier mobility of CMOS transistors as well as to boost and tune the performance of optoelectronic devices, enabling wavelength tuning, polarization selectivity and suppression of temperature drifts. Semiconducting nanowires benefit from enhanced mechanical properties, such as increased yield...

We have fabricated and characterized YBa2Cu3O7-δ grain boundary junctions to determine their feasibility as tunnel barriers in single electron transistors. Superconducting quantum interference devices with injection lines have been used to measure the junctions capacitance. We have extracted capacitance values which allow us to achieve a Coulomb bl...

In this work we investigate doping by solid-state diffusion from a doped oxide layer, obtained by plasma-enhanced chemical vapor deposition (PECVD), as a means for selectively doping silicon nanowires (NWs). We demonstrate both n-type (phosphorous) and p-type (boron) doping up to concentrations of 10(20) cm(-3), and find that this doping mechanism...