SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Samuelson Lars) ;pers:(Pettersson Håkan)"

Sökning: WFRF:(Samuelson Lars) > Pettersson Håkan

  • Resultat 1-10 av 64
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Bordag, Michael, et al. (författare)
  • Shear stress measurements on InAs nanowires by AFM manipulation
  • 2007
  • Ingår i: Small. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 3:8, s. 1398-1401
  • Tidskriftsartikel (refereegranskat)abstract
    • On an upward curve? The curvature of an elastically deformed nanowire pinned to a flat surface contains information about the maximum static friction force, and hence the shear stress, between the nanowire and the surface. Here, InAs nanowires are bent in a controlled manner using the tip of an atomic force microscope (see image). The shear stress can be obtained from a simple analysis according to the standard theory of elasticity.
  •  
2.
  • Conache, Gabriela, et al. (författare)
  • AFM-based manipulation of InAs nanowires
  • 2008
  • Ingår i: Proceedings of the IVC-17 (17th International Vacuum Congress) [also] ICSS-13 (13th International Conference on Surface Science) [also] ICN+T-2007 (International Conference on Nanoscience and Technology). - Bristol : Institute of Physics (IOP). ; 100, s. 052051-052051
  • Konferensbidrag (refereegranskat)abstract
    • A controlled method of manipulation of nanowires was found using the tip of an Atomic Force Microscope (AFM). Manipulation is done in the ‘Retrace Lift’ mode, where feedback is turned off for the reverse scan and the tip follows a nominal path. The effective manipulation force during the reverse scan can be changed by varying an offset in the height of the tip over the surface. Using this method, we have studied InAs nanowires on different substrates. We have also investigated interactions between wires and with gold features patterned onto the substrates.
  •  
3.
  • Conache, Gabriela, et al. (författare)
  • Bias-controlled friction of InAs nanowires on a silicon nitride layer studied by atomic force microscopy
  • 2010
  • Ingår i: Physical Review B Condensed Matter. - College Park, Md. : American Physical Society. - 0163-1829 .- 1095-3795. ; 82:3
  • Tidskriftsartikel (refereegranskat)abstract
    • By studying how nanowires lying on a surface bend when pushed by an atomic force microscopy tip we are able to measure the friction between them and the substrate. Here, we show how the friction between InAs nanowires and an insulating silicon nitride layer varies when a dc voltage is applied to the tip during manipulation. The bias charges the capacitor formed by the wire and the grounded silicon back contact. Electrostatic forces increase the contact pressure and allow us to tune the friction between the wire and the silicon nitride surface. Using nanowires of about 40-70 nm diameter and a few microns in length we have applied biases in the range +12 to -12 V. A monotonic increase of the sliding friction with voltage was observed. This increase in friction with the normal force implies that the mesoscopic nanowire-surface system behaves like a macroscopic contact, despite the nanometer size of the contact in the direction of motion. The demonstrated bias-controlled friction has potential applications in MEMS/NEMS devices.
  •  
4.
  • Conache, Gabriela, et al. (författare)
  • Comparative friction measurements of InAs nanowires on three substrates
  • 2010
  • Ingår i: Journal of Applied Physics. - College Park, MD : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 108:9
  • Tidskriftsartikel (refereegranskat)abstract
    • We have investigated friction between InAs nanowires and three different substrates: SiO2, fluorosilanized SiO2, and Si3N4. The nanowires were pushed laterally with the tip of an atomic force microscope and the friction force per unit length for both static and sliding friction was deduced from the equilibrium shape of the bent wires. On all three substrates, thick wires showed a difference between sliding and static friction of up to three orders of magnitude. Furthermore, all substrates display a transition to stick-slip motion for nanowires with a diameter of less than about 40 nm. Hydrophobic and hydrophilic substrates display similar friction behavior suggesting that a condensed water layer does not strongly influence our results. The patterns and trends in the friction data are similar for all three substrates, which indicates that they are more fundamental in character and not specific to a single substrate. ©2010 American Institute of Physics.
  •  
5.
  • Conache, Gabriela, et al. (författare)
  • Friction measurements of InAs nanowires on Silicon nitride by AFM manipulation
  • 2009
  • Ingår i: Small. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 5:2, s. 203-207
  • Tidskriftsartikel (refereegranskat)abstract
    • A study was conducted to perform friction measurements of InAs nanowires (NW) on silicon nitride (Si 3N 4) through atomic force microscopy (AFM) manipulation. The investigations revealed the friction force per unit length for sliding and static friction over a range of nanowire diameters. It was found that there is a significant difference between the coefficients of the two sliding modes for large wires. It was also found that the difference between the two sliding modes disappears at smaller diameters and the sliding friction becomes equal with the static friction. The AFM investigations were performed on a Nanoscope IIIa Dimension 3100, using rectangular cantilevers, with a nominal spring constant of 30 N m -1. The nanowires were manipulated, using the 'Retrace Lift' mode of the AFM controller. The friction force per unit length was gathered from the local curvature of the NWs, using standard elasticity theory.
  •  
6.
  • Conache, Gabriela, 1977-, et al. (författare)
  • Nanowire friction with an applied bias
  • 2009
  • Konferensbidrag (refereegranskat)abstract
    • Recently, we have shown how the friction acting on nanowires pushed across a surface by an AFM tip can be determined by measuring the radius of curvature of the bent wire aŸer manipulation. This technique allows us to study the friction properties of an extended mesoscale contact. Our main focus has been to determine whether such contacts behave like macroscopic objects, in which dišerences between the 'true' and 'apparent' contact areas play a key role and friction varies linearly with the applied normal force, or whether they are more like atomic-scale point contacts, wheremore fundamental processes dominate and friction oŸen is independent of the normal force. In this work we show how the friction between InAs nanowires and an insulating silicon nitride layer on a conductive silicon substrate varies when a DC voltage is applied to the AFM tip during manipulation. e tip charges the capacitor formed by the wire and the grounded silicon back contact, giving rise to attractive Coulomb forces and thus increasing the contact pressure between the wire and the silicon nitride. In this way we can vary the normal force on the sliding surfaces using a single wire, with a constant structure and contact geometry. Using nanowires of about 40-50 nm diameter and a few microns in length we have applied tip voltages in the range +12 to -12 V. Simplemodeling indicates that these voltages su›ce to give similar levels of band-lling and depletion to when the same wires are used in working wrap-gate or back-gate devices. A monotonic increase of the sliding friction with the voltage applied on the tip was observed. is implies that the friction increases with the normal force and that this mesoscopic system behaves more like a macroscopic contact, despite the nanometer size of the contact in the direction of motion.
  •  
7.
  • Jain, Vishal, 1989-, et al. (författare)
  • A comparative study of nanowire based infrared p+-i-n+ photodetectors
  • 2012
  • Konferensbidrag (refereegranskat)abstract
    • We present a comparative study of electrical and optical properties of two types of p+-i-n+ photodetectors based on self-assembled ensembles of vertical InP nanowires (NWs) monolithically grown on InP. The detectors differ in the type of p+ contact, one detector geometry has p+-i-n+ segments integrated into the NWs (type A) while the other detector has i-n+ NW segments grown directly on a p+ substrate(type B). The samples were prepared by first depositing 80 nm Au nanoparticles on a p+ InP substrate using an aerosol technique and subsequently growing NWs using MOVPE. The NWs have a polytypecrystal structure of alternating wurtzite and zincblende segments. The processing of the detectors include deposition of SiO2, followed by an etching step to remove the oxide from the tip of the NWs, and finally sputtering of ITO on 1x1 mm2 device areas. The two most prominent differences between the detectors concern the current-voltage (I-V) characteristics and the spatial location of generated photocurrent. From spectrally resolved photocurrent measurements, we conclude that the photocurrent in detector type A is primarily generated in the NWs, whereas the photocurrent in type B detectors mainly stems from the substrate. Photogenerated carriers in the substrate diffuse to the NWs where they are effectively funnelled into the NWs. The I-V characteristics of the type A detector displays a non-trivial transport behaviour for forward biases, whereas type B shows excellent rectifying behavior with an ideality factor of about 2.5. We will discuss detailed analysis of the spectral fingerprints of the two detector types revealing the mixed crystal phase of the polytype NWs and bandstructure effects, temperature dependence of the I-V characteristics and typical photodetector parameters.
  •  
8.
  • Pettersson, Håkan, 1962-, et al. (författare)
  • Electrical and optical properties of InP nanowire ensemble p(+)-i-n(+) photodetectors
  • 2012
  • Ingår i: Nanotechnology. - Bristol, UK : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 23:13
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on a comprehensive study of electrical and optical properties of efficient near-infrared p(+)-i-n(+) photodetectors based on large ensembles of self-assembled, vertically aligned i-n(+) InP nanowires monolithically grown on a common p(+) InP substrate without any buffer layer. The nanowires have a polytype modulated crystal structure of wurtzite and zinc blende. The electrical data display excellent rectifying behavior with an ideality factor of about 2.5 at 300 K. The ideality factor scales with 1/T, which possibly reflects deviations from classical transport models due to the mixed crystal phase of the nanowires. The observed dark leakage current is of the order of merely similar to 100 fA/nanowire at 1 V reverse bias. The detectors display a linear increase of the photocurrent with reverse bias up to about 10 pA/nanowire at 5 V. From spectrally resolved measurements, we conclude that the photocurrent is primarily generated by funneling photogenerated carriers from the substrate into the NWs. Contributions from direct excitation of the NWs become increasingly important at low temperatures. The photocurrent decreases with temperature with an activation energy of about 50 meV, which we discuss in terms of a temperature-dependent diffusion length in the substrate and perturbed transport through the mixed-phase nanowires. © 2012 IOP Publishing Ltd.
  •  
9.
  • Pettersson, Håkan, et al. (författare)
  • Friction measurements on InAs NWs by AFM manipulation
  • 2008
  • Konferensbidrag (refereegranskat)abstract
    • We discuss a new approach to measure the friction force between elastically deformed nanowires and a surface. The wires are bent, using an AFM, into an equilibrium shape determined by elastic restoring forces within the wire and friction between the wire and the surface. From measurements of the radius of curvature of the bent wires, elasticity theory allows the friction force per unit length to be calculated. We have studied friction properties of InAs nanowires deposited on SiO2, silanized SiO2 and Si3N4 substrates. The wires were typically from 0.5 to a few microns long, with diameters varying between 20 and 80 nm. Manipulation is done in a `Retrace Lift' mode, where feedback is turned off for the reverse scan and the tip follows a nominal path. The effective manipulation force during the reverse scan can be changed by varying an offset in the height of the tip over the surface. We will report on interesting static- and sliding friction experiments with nanowires on the different substrates, including how the friction force per unit length varies with the diameter of the wires.
  •  
10.
  • Pettersson, Håkan, et al. (författare)
  • Infrared Photodetectors in Heterostructure Nanowires
  • 2006
  • Ingår i: Nano letters (Print). - Washington : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 6:2, s. 229-232
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on spectrally resolved photocurrent measurements on single self-assembled nanowire heterostructures. The wires, typically 3 μm long with an average diameter of 85 nm, consist of InAs with a 1 μm central part of InAsP. Two different sets of wires were prepared with phosphorus contents of 15 ±3% and 35 ±3%, respectively, as determined by energy-dispersive spectroscopy measurements made in transmission electron microscopy. Ohmic contacts are fabricated to the InAs ends of the wire using e-beam lithography. The conduction band offset between the InAs and InAsP regions virtually removes the dark current through the wires at low temperature. In the optical experiments, interband excitation in the phosphorus-rich part of the wires results in a photocurrent with threshold energies of about 0.65 and 0.82 eV, respectively, in qualitative agreement with the expected band gap of the two compositions. Furthermore, a strong polarization dependence is observed with an order of magnitude larger photocurrent for light polarized parallel to the wire than for light polarized perpendicular to the wire. We believe that these wires form promising candidates as nanoscale infrared polarization-sensitive photodetectors.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 64
Typ av publikation
tidskriftsartikel (38)
konferensbidrag (22)
bokkapitel (2)
doktorsavhandling (1)
licentiatavhandling (1)
Typ av innehåll
refereegranskat (60)
övrigt vetenskapligt/konstnärligt (4)
Författare/redaktör
Samuelson, Lars (61)
Pettersson, Håkan, 1 ... (30)
Borgström, Magnus (20)
Heurlin, Magnus (15)
Montelius, Lars (11)
visa fler...
Borgström, Magnus T. (10)
Jain, Vishal, 1989- (10)
Suyatin, Dmitry (9)
Fröberg, Linus (9)
Ribayrol, Aline (9)
Canali, Carlo M. (8)
Nowzari, Ali (8)
Kumar, Sandeep (8)
Ronning, Carsten (8)
Wallentin, Jesper (7)
Capasso, Federico (7)
Borschel, Christian (7)
Karimi, Mohammad, 19 ... (7)
Karimi, Mohammad (6)
Conache, Gabriela (6)
Gray, Struan (6)
Liu, Ruisheng (6)
Zeng, Xulu (5)
Storm, Kristian (5)
Messing, Maria (5)
Trägårdh, Johanna (5)
Canali, Carlo (5)
Jain, Vishal (5)
Landin, Lars (5)
Seifert, Werner (4)
Berg, Alexander (4)
Bordag, Michael (4)
Limpert, Steven (4)
Jafari Jam, Reza (4)
Graczyk, Mariusz (3)
Maximov, Ivan (3)
Lindgren, David (3)
Gustafsson, Anders (3)
Landin, Lars, 1948- (3)
Wagner, Jakob (3)
Linke, Heiner (3)
Jacobsson, Daniel (3)
Wickert, Peter (3)
Paschoal, Waldomiro, ... (3)
Canali, C. M. (3)
Michalak, L (3)
Conache, Gabriela, 1 ... (3)
Witzigmann, Bernd (3)
Michalak, Lukasz (3)
visa färre...
Lärosäte
Högskolan i Halmstad (60)
Lunds universitet (38)
Linnéuniversitetet (6)
Göteborgs universitet (1)
Kungliga Tekniska Högskolan (1)
Chalmers tekniska högskola (1)
visa fler...
RISE (1)
visa färre...
Språk
Engelska (64)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (60)
Teknik (37)
Medicin och hälsovetenskap (1)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy