Properties of InAs/InAlAs heterostructures

Affentauschegg, Cedric; Wieder, H. H.

doi:10.1088/0268-1242/16/8/313

Cited by 47 publications

(52 citation statements)

References 24 publications

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“…25 We attribute the increase of the field-effect mobility with the increasing doping factor to the change of carrier distribution within the nanowire. It was found by Affentauschegg and Wieder 41 that, due to the additional contribution of surface scattering, the mobility of electrons at the surface is considerably lower than the respective bulk value. As shown in Fig.…”

Section: à3mentioning

confidence: 96%

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Effect of Si-doping on InAs nanowire transport and morphology

Wirths¹,

Weis²,

Winden³

et al. 2011

Journal of Applied Physics

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The effect of Si-doping on the morphology, structure, and transport properties of nanowires was investigated. The nanowires were deposited by selective-area metal organic vapor phase epitaxy in an N 2 ambient. It is observed that doping systematically affects the nanowire morphology but not the structure of the nanowires. However, the transport properties of the wires are greatly affected. Room-temperature four-terminal measurements show that with an increasing dopant supply the conductivity monotonously increases. For the highest doping level the conductivity is higher by a factor of 25 compared to only intrinsically doped reference nanowires. By means of back-gate field-effect transistor measurements it was confirmed that the doping results in an increased carrier concentration. Temperature dependent resistance measurements reveal, for lower doping concentrations, a thermally activated semiconductor-type increase of the conductivity. In contrast, the nanowires with the highest doping concentration show a metal-type decrease of the resistivity with decreasing temperature.

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Section: à3mentioning

confidence: 96%

“…For the surface Fermi level pinning a value of 160 meV was assumed. 40,41 Due to surface Fermi level pinning, the conduction band is bent downwards at the surface. This induces a surface accumulation layer, indicated by the maximum of n at about 10 nm beneath the surface.…”

Section: à3mentioning

confidence: 99%

Effect of Si-doping on InAs nanowire transport and morphology

Wirths¹,

Weis²,

Winden³

et al. 2011

Journal of Applied Physics

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“…The intrinsic donor-like surface states of InAs play a major role in determining transport properties 7 , and lead to reduced electron mobilities at low temperatures due to ionized impurity scattering 8 . The charged surface states produce a random spatial electrostatic potential in the nanowire, which may contribute to the spontaneous formation of quantum dots at low temperature 9 .…”

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confidence: 99%

Electron transport in InAs-InAlAs core-shell nanowires

Holloway

Song

Haapamaki

et al. 2013

Applied Physics Letters

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Evidence is given for the effectiveness of InAs surface passivation by the growth of an epitaxial In 0.8 Al 0.2 As shell. The electron mobility is measured as a function of temperature for both core-shell and unpassivated nanowires, with the core-shell nanowires showing a monotonic increase in mobility as temperature is lowered, in contrast to a turnover in mobility seen for the unpassivated nanowires. We argue that this signifies a reduction in low temperature ionized impurity scattering for the passivated nanowires, implying a reduction in surface states. Core-shell nanowires were grown in a gas source molecular beam epitaxy system using Au seed particles 16 . First, InAs cores were grown axially by the Au assisted vapour liquid solid mechanism on a p-GaAs (111)B substrate at a growth temperature of 420This was followed by the inclusion of Al to facilitate radial growth of the In 0.8 Al 0.2 As shell 17 .The nanowires were characterized using transmission electron microscopy (TEM).As-grown nanowires were sonicated and suspended in ethanol, dispersed onto TEM grids have an inner core and an outer shell structure. In general, the nanowires had a core diameter of 20-50 nm and a shell that was 12-15 nm thick, independent of core diameter. The chemical composition of the nanowires was analyzed by energy-dispersive x-ray spectroscopy (EDS). As shown in Figure 1a, the EDS line scan analysis along the radial direction showsIn and As in the core region and In, As and Al in the shell region. High-resolution TEM (HRTEM) image of a representative unetched nanowire in Figure 1b clearly shows lattice 3 fringes of a single-crystal nanowire along the [2110] zone axis. Both core and shell exhibit wurtzite crystal structure, evidenced by ABAB... stacking, and confirmed by selected area diffraction. HRTEM and electron diffraction data are both consistent with a dislocation-free core-shell interface for these nanowires. However, at higher Al concentrations, dislocations due to relaxation of the core-shell interface are observed 17 . The nanowires studied here had low stacking fault densities, achieved by using sufficiently low growth rates 17,18 . Below, we also show data from unpassivated InAs nanowires that were grown under nominally identical conditions to the growths of the nanowire cores mentioned previously, except that the axial growth rate was 0.25 µm/hr and 0.5 µm/hr for the core-shell and bare nanowires, respectively.FET devices were fabricated using a standard e-beam lithography technique. As-grown nanowires were mechanically deposited onto a 175 nm thick SiO 2 layer above a n ++ -Si substrate. Selected nanowires with diameters 40−80nm were located relative to pre-existing fiducial markers by scanning electron microscopy (SEM), with care taken to minimize the electron dose. The contact areas were etched with citric acid to remove the shell material, followed by room temperature sulfur passivation to prevent oxide regrowth 19 during the sample transfer to an e-beam metal evaporator. Ni/Au (30nm/50nm) metal contacts were...

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“…Possible influences of the surface electric field were usually written off due to a narrow band gap in InAs and potentially small band bending at the surface of this material. This is not always justifiable, because surface potential in InAs is fixed at fairly high ( 0.2 eV [51]) energies above the conduction band edge and in p-doped crystal the surface depletion layer can be sufficiently wide and strong. It has been discovered in [52] that p-type InAs is a better THz emitter than n-type InAs, and this was explained by a contribution of the EFIOR effect.…”

Section: Indium Arsenidementioning

confidence: 99%

Semiconductor materials for ultrafast optoelectronic applications

Krotkus¹,

Bertulis²,

Adomavičius³

et al. 2009

Lithuanian J. Phys.

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The paper presents a review of experimental investigations of various semiconductor materials used for the development of ultrafast optoelectronic devices activated by femtosecond laser pulses that have been performed at the Optoelectronics Laboratory of the Semiconductor Physics Institute during the period from 1997 to 2008. Technology and physical characteristics of low-temperature-grown GaAs and GaBiAs layers as well as the effect of terahertz radiation from the femtosecond laser excited semiconductor surfaces are described and analysed.

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Properties of InAs/InAlAs heterostructures

Cited by 47 publications

References 24 publications

Effect of Si-doping on InAs nanowire transport and morphology

Effect of Si-doping on InAs nanowire transport and morphology

Electron transport in InAs-InAlAs core-shell nanowires

Semiconductor materials for ultrafast optoelectronic applications

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