References of "Calarco, Raffaella"
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See detailQuantum transport in narrow-gap semiconductor nanocolumns
Lüth, Hans; Blömers, Christian; Richter, Thomas et al

in Physica Status Solidi C. Current Topics in Solid State Physics (2010), 7(2), 386-389

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See detailPhase-coherent transport in InN nanowires of various sizes
Blömers, Ch UL; Schäpers, T.; Richter, T. UL et al

in Physical Review (2008), B 77(20),

We investigate phase-coherent transport in InN nanowires of various diameters and lengths. The nanowires were grown by means of plasma-assisted molecular beam epitaxy. Information on the phase-coherent ... [more ▼]

We investigate phase-coherent transport in InN nanowires of various diameters and lengths. The nanowires were grown by means of plasma-assisted molecular beam epitaxy. Information on the phase-coherent transport is gained by analyzing the characteristic fluctuation pattern in the magnetoconductance. For a magnetic field oriented parallel to the wire axis, we found that the correlation field mainly depends on the wire cross section, while the fluctuation amplitude is governed by the wire length. In contrast, if the magnetic field is perpendicularly oriented, for wires longer than approximately 200 nm, the correlation field is limited by the phase coherence length. Further insight into the orientation dependence of the correlation field is gained by measuring the conductance fluctuations at various tilt angles of the magnetic field. [less ▲]

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See detailInvestigation on Localized States in GaN Nanowires
Polenta, L. UL; Rossi, M.; Cavallini, Anna et al

in ACS Nano (2008), 2

GaN nanowires with diameters ranging between 50 and 500 nm were investigated by electrical and photoinduced current techniques to determine the influence of their size on the opto-electronic behavior of ... [more ▼]

GaN nanowires with diameters ranging between 50 and 500 nm were investigated by electrical and photoinduced current techniques to determine the influence of their size on the opto-electronic behavior of nanodevices. The conductivity, photoconductivity, and persistent photoconductivity behavior of GaN nanowires are observed to strongly depend on the wire diameter. In particular, by spectral photoconductivity measurements, three main sub-band-gap optoelectronic transitions were detected, ascribed to the localized states giving rise to the characteristic blue, green, and yellow bands of GaN. Photoconductivity with below-band-gap excitation varies orders of magnitude with the wire diameter, similarly to that observed for near-band-edge excitation. Moreover, yellow-band-related signal shows a superlinear behavior with respect to the band-edge signal, offering new information for the modeling of the carrier recombination mechanism along the nanowires. The photoconductivity results agree well with a model which takes into account a uniform distribution of the localized states inside the wire and their direct recombination with the electrons in the conduction band. [less ▲]

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See detailDoping Concentration of GaN Nanowires Determined by Opto-Electrical Measurements
Richter, T. UL; Lüth, H.; Meijers, R. et al

in Nano Letters (2008), 8(9), 3056-3059

The influence of n-doping on the electrical transport properties of GaN nanowires is investigated by photoconductivity measurements on wires with different diameters. The electrical transport in nanowires ... [more ▼]

The influence of n-doping on the electrical transport properties of GaN nanowires is investigated by photoconductivity measurements on wires with different diameters. The electrical transport in nanowires is extremely sensitive to the wire diameter because of the size dependent barrier for surface recombination. This effect is used to determine the doping level of the nanowires and to complete and consolidate our previously developed surface recombination model for GaN nanowires. [less ▲]

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See detailAcoustic charge transport in GaN nanowires
Ebbecke, J.; Maisch, S.; Wixforth, A. et al

in Nanotechnology (2008), 19(27), 275708-5

We present acoustic charge transport in GaN nanowires (GaN NWs). The GaN NWs were grown by molecular beam epitaxy (MBE) on silicon(111) substrates. The nanowires were removed from the silicon substrate ... [more ▼]

We present acoustic charge transport in GaN nanowires (GaN NWs). The GaN NWs were grown by molecular beam epitaxy (MBE) on silicon(111) substrates. The nanowires were removed from the silicon substrate, aligned using surface acoustic waves (SAWs) on the piezoelectric substrate LiNbO3 and finally contacted by electron beam lithography. Then, a SAW was used to create an acoustoelectric current in the GaN NWs which was detected as a function of radio-frequency (RF) wave frequency and its power. The presented method and our experimental findings open up a route towards new acoustic charge transport nanostructuredevices in a wide bandgap material such as GaN. [less ▲]

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See detailTemperature-dependence of the phase-coherence length in InN nanowires
Blömers, Ch UL; Schäpers, Th; Richter, T. UL et al

in Applied Physics Letters (2008), 92(13), 132101-132103

We report on low-temperature magnetotransport measurements on InN nanowires, grown by plasma-assisted molecular beam epitaxy. The characteristic fluctuation pattern observed in the conductance was ... [more ▼]

We report on low-temperature magnetotransport measurements on InN nanowires, grown by plasma-assisted molecular beam epitaxy. The characteristic fluctuation pattern observed in the conductance was employed to obtain information on phase-coherent transport. By analyzing the root mean square and the correlation field of the conductance fluctuations at various temperatures, the phase-coherence length was determined. [less ▲]

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See detailGaN and InN nanowires grown by MBE: A comparison
Calarco, Raffaella; Marso, Michel UL

in Applied Physics A : Materials Science & Processing (2007)

Morphological, optical and transport properties of GaN and InN nanowires grown by molecular beam epitaxy (MBE) have been studied. The differences between the two materials in respect to growth parameters ... [more ▼]

Morphological, optical and transport properties of GaN and InN nanowires grown by molecular beam epitaxy (MBE) have been studied. The differences between the two materials in respect to growth parameters and optimization procedure was stressed. The nanowires crystalline quality has been investigated by means of their optical properties. A comparison of the transport characteristics was given. For each material a band schema was shown, which takes into account transport and optical features and is based on Fermi level pinning at the surface. [less ▲]

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See detailDefect Distribution along Single GaN Nanowhiskers
Cavallini, Anna; Polenta, Laura; Rossi, Marco et al

in Nano Letters (2006), 6(7), 1548-1551

In this letter we report on spectral photoconductivity (PC) on different sections of single MBE-grown GaN nanowhiskers of diameters ranging on the order of 100 nm. The photoconductivity spectra show ... [more ▼]

In this letter we report on spectral photoconductivity (PC) on different sections of single MBE-grown GaN nanowhiskers of diameters ranging on the order of 100 nm. The photoconductivity spectra show, besides the band-gap related transition, deep-levels corresponding to the yellow, green, and blue bands. A strong spatial localization of specific photocurrent peaks has been observed, indicating that the defects responsible for such transitions are distributed inhomogeneously along the column growth direction. [less ▲]

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See detailSize-dependent Photoconductivity in MBE-Grown GaN-Nanowires
Calarco, Raffaella; Marso, Michel UL; Richter, Thomas et al

in Nano Letters (2005), 5(5), 981-984

We report on electrical transport in the dark and under ultraviolet (UV) illumination through GaN nanowhiskers grown by molecular beam epitaxy (MBE), which is sensitively dependent on the column diameter ... [more ▼]

We report on electrical transport in the dark and under ultraviolet (UV) illumination through GaN nanowhiskers grown by molecular beam epitaxy (MBE), which is sensitively dependent on the column diameter. This new effect is quantitatively described by a size dependent surface recombination mechanism. The essential ingredient for the interpretation of this effect is a diameter dependent recombination barrier, which arises from the interplay between column diameter and space charge layer extension at the column surface. [less ▲]

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See detailGaN Nanocolumns on Si(111) Grown b Molecular Beam Epitaxy
Calarco, Raffaella; Marso, Michel UL; Meijers, R. et al

in Proc. 5th Intern. Conf. Advanced Semicon. Dev. & Microsystems ASDAM’04 (2004)

GaN nanocolumns are reproducibly grown by plasma-assisted molecular beam epitaxy on Si(111). The nanocolumn density and diameter, 20–150 nm, are controlled by means of the III/V ratio. The nanocolumns ... [more ▼]

GaN nanocolumns are reproducibly grown by plasma-assisted molecular beam epitaxy on Si(111). The nanocolumn density and diameter, 20–150 nm, are controlled by means of the III/V ratio. The nanocolumns grow parallel to the [111] direction of the Si substrate. The columns have been transferred to a Si(100) substrate covered with a layer of 300nm SiO2; single nanowire devices have been fabricated using finger shaped electrical contacts (Ti/Au) obtained by e-beam patterning technique. The electrical transport properties of the resulting metal–semiconductor–metal nanostructures are analyzed by means of current– voltage measurements with and without UV-illumination. [less ▲]

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