Experimental determination of adatom diffusion lengths for growth of InAs nanowires

Madsen, Morten Hannibal; Krogstrup, Peter; Johnson, Erik; Venkatesan, Sriram; Mühlbauer, Erika; Scheu, Christina; Sørensen, C. B.; Nygård, Jesper

doi:10.1016/j.jcrysgro.2012.12.001

Cited by 45 publications

(78 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A weak interdot tunnel coupling compared to the tunnel rates to the leads, 12 1 , 2 , suggests that the transmission through the DQD is limited by 12 and the individual QDs can be assumed to be either filled or empty. This picture is illustrated in Fig.…”

Section: Double Dot Mr and Mrsmentioning

confidence: 99%

“…It consists of a ∼80 nm diameter InAs NW deposited by spin coating on a Si ++ /SiO 2 substrate and contacted by source (S) and drain (D) Ti/Au (5 nm/70 nm) contacts. The NWs were grown by solid-source molecular beam epitaxy [12] implementing a two-step growth process to suppress stacking faults [13]. We used standard lock-in techniques to measure the differential conductance G = dI/dV as a function of the bias V at a base temperature of 230 mK in a 3 He cryostat.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Magnetoresistance engineering and singlet/triplet switching in InAs nanowire quantum dots with ferromagnetic sidegates

et al. 2016

View full text Add to dashboard Cite

We present magnetoresistance (MR) experiments on an InAs nanowire quantum dot device with two ferromagnetic sidegates (FSGs) in a split-gate geometry. The wire segment can be electrically tuned to a single dot or to a double dot regime using the FSGs and a backgate. In both regimes we find a strong MR and a sharp MR switching of up to 25% at the field at which the magnetizations of the FSGs are inverted by the external field. The sign and amplitude of the MR and the MR switching can both be tuned electrically by the FSGs. In a double dot regime close to pinch-off we find two sharp transitions in the conductance, reminiscent of tunneling MR (TMR) between two ferromagnetic contacts, with one transition near zero and one at the FSG switching fields. These surprisingly rich characteristics we explain in several simple resonant tunneling models. For example, the TMR-like MR can be understood as a stray-field controlled transitions between singlet and triplet double dot states. Such local magnetic fields are the key elements in various proposals to engineer novel states of matter and may be used for testing electron spin based Bell inequalities.

show abstract

Section: Double Dot Mr and Mrsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetoresistance engineering and singlet/triplet switching in InAs nanowire quantum dots with ferromagnetic sidegates

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Detailed discussion on growth parameters and procedures were explained elsewhere. 25 Conventional TEM experiments were performed in a FEI Titan 80-300 S/TEM operated at 300 kV. Atomic resolution high-angle annular dark-field (HAADF) Z-contrast imaging and high resolution X-ray energy-dispersive spectroscopy (EDS)/spectroscopic imaging by X-rays (SIX) experiments were carried out using an advanced probe Cs-corrected analytical TEM/STEM system JEM-ARM 200CF with cold field-emission gun (C-FEG) operated at 200 kV.…”

mentioning

confidence: 99%

“…Maintaining a Ga concentration corresponding to x $ 0.35 in each Ga x In 1Àx As segment ensures a high fraction of straight axially grown nanowires. 24,25 The wires predominantly exhibits the hexagonal wurtzite (WZ) structure and the preferential growth direction is along the hexagonal closed packed [0001] WZ as inferred from electron diffraction data shown in Figure 2(b). 23,[26][27][28] Our analysis of the multiple Ga Ga x In 1Àx As/InAs interface in Z-contrast HAADF-STEM imaging as shown in Figure 1(b).…”

mentioning

confidence: 99%

Direct observation of interface and nanoscale compositional modulation in ternary III-As heterostructure nanowires

Venkatesan

Madsen

Schmid

et al. 2013

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

Straight, axial InAs nanowire with multiple segments of Ga x In 1−x As were grown. High resolution X-ray energy-dispersive spectroscopy (EDS) mapping reveal the distribution of group III atoms at the axial interfaces and at the sidewalls. Significant Ga enrichment, accompanied by a structural change is observed at the Ga x In 1−x As/InAs interfaces and a higher Ga concentration for the early grown Ga x In 1−x As segments. The elemental map and EDS line profile infer Ga enrichment at the facet junctions between the sidewalls. The relative chemical potentials of ternary alloys and the thermodynamic driving force for liquid to solid transition explains the growth mechanisms behind the enrichment.

show abstract

“…The NWs attain the wurtzite crystal structure with the [0001] direction along the NW axis and grow to a length of ~7 µm with a tapered profile having diameters of ~130 nm at the base and 40 nm at the tip 18 .…”

mentioning

confidence: 99%

Raman spectroscopy and electrical properties of InAs nanowires with local oxidation enabled by substrate micro-trenches and laser irradiation

Tanta

Madsen

Liao

et al. 2015

Applied Physics Letters

View full text Add to dashboard Cite

The thermal gradient along indium-arsenide nanowires was engineered by a combination of fabricated micro-trenches in the supporting substrate and focused laser irradiation. This allowed local control of thermally activated oxidation reactions of the nanowire on the scale of the diffraction limit. The locality of the oxidation was detected by microRaman mapping, and the results were found consistent with numerical simulations of the temperature profile. Applying the technique to nanowires in electrical devices the locally oxidized nanowires remained conducting with a lower conductance as expected for an effectively thinner conducting core.Semiconductor nanowires (NWs) offer a range of properties which makes them attractive to diverse areas of research and technology. The reduced size and high surfaceto-volume ratio make them promising candidates for advanced electronics . Also, the confinement offered by the NW geometry may allow devices providing greatly enhanced thermoelectric properties 7,8 . In order to exploit the potential of semiconductor NWs for devices with improved or new functionalities, methods of locally controlling the properties along the NWs are often required. Such control has been demonstrated either by advanced device architectures incorporating local electrostatic gates 9,10 or by modifying the crystal properties along the wire by changing material composition during or after growth [11][12][13] . An alternative approach which has recently emerged is the possibility of using a high intensity focused laser beam to locally induce chemical changes in the NW 14 . By combination of Raman spectroscopy 15 and transmission electron microscopy 16 it has been established that for the case of InAs the high intensity laser, in the presence of ambient air conditions, promotes the oxidation process As 2 O 3 +2InAs→In 2 O 3 +4As which converts the irradiated parts of the NW surface to crystalline arsenic and polycrystalline indium oxide 16. However, so far, only little is known about the properties of the resulting structures and the spatial resolution that can be achieved has not been analyzed. A similar process occurs for GaAs, and Yazji, S. et al 17 showed that the thermal conductivity of the NW is dramatically decreased upon irradiation, suggesting this method as a way of designing structures with enhanced thermoelectric properties.Here we show that by suspending NWs over microtrenches etched into a SiO 2 substrate the temperature profile of the NW can be locally engineered. By tuning the laser intensity, only the suspended parts of the wires will reach a temperature sufficient to activate the oxidation process.Using Raman spectroscopy we demonstrate the viability of this approach, achieving a spatial resolution of at least 250 nm; the size of the detection area of our Raman setup. Finally, we study the electrical properties of the oxidized NWs and show that they maintain their ability to carry electrical current and also preserve the key semiconductor property of electrostatic tunability using a nearby ...

show abstract

Experimental determination of adatom diffusion lengths for growth of InAs nanowires

Cited by 45 publications

References 37 publications

Magnetoresistance engineering and singlet/triplet switching in InAs nanowire quantum dots with ferromagnetic sidegates

Magnetoresistance engineering and singlet/triplet switching in InAs nanowire quantum dots with ferromagnetic sidegates

Direct observation of interface and nanoscale compositional modulation in ternary III-As heterostructure nanowires

Raman spectroscopy and electrical properties of InAs nanowires with local oxidation enabled by substrate micro-trenches and laser irradiation

Contact Info

Product

Resources

About