Direct observation of acoustic oscillations in InAs nanowires

TY - JOUR

T1 - Direct observation of acoustic oscillations in InAs nanowires

AU - Mariager, Simon Oddsson

AU - Khakhulint, Dmitry

AU - Lemket, Henrik T.

AU - Kjært, Kasper S.

AU - Guerin, Laurent

AU - Nuccio, Laura

AU - Sørensen, Claus Birger

AU - Nielsen, Martin Meedom

AU - Feidenhans'l, Robert Krarup

PY - 2010/7/14

Y1 - 2010/7/14

N2 - Time-resolved X-ray diffraction and optical reflectivity are used to directly measure three different acoustic oscillations of InAs nanowires. The oscillations are excited by a femtosecond laser pulse and evolve at three different time scales. We measure the absolute scale of the initial radial expansion of the fundamental breathing eigenmode and determine the frequency by transient optical reflectivity. For the extensional eigenmode we measure the oscillations of the average radial and axial lattice constants and determine the amplitude of oscillations and the average extension. Finally we observe a bending motion of the nanowires. The frequencies of the eigenmodes are in good agreements with predictions made by continuum elasticity theory and we find no difference in the speed of sound between the wurtzite nanowires and cubic bulk crystals, but the measured strain is influenced by the interaction between different modes. The wurtzite crystal structure of the nanowires however has an anisotropic thermal expansion.

AB - Time-resolved X-ray diffraction and optical reflectivity are used to directly measure three different acoustic oscillations of InAs nanowires. The oscillations are excited by a femtosecond laser pulse and evolve at three different time scales. We measure the absolute scale of the initial radial expansion of the fundamental breathing eigenmode and determine the frequency by transient optical reflectivity. For the extensional eigenmode we measure the oscillations of the average radial and axial lattice constants and determine the amplitude of oscillations and the average extension. Finally we observe a bending motion of the nanowires. The frequencies of the eigenmodes are in good agreements with predictions made by continuum elasticity theory and we find no difference in the speed of sound between the wurtzite nanowires and cubic bulk crystals, but the measured strain is influenced by the interaction between different modes. The wurtzite crystal structure of the nanowires however has an anisotropic thermal expansion.

U2 - 10.1021/nl100798y

DO - 10.1021/nl100798y

M3 - Journal article

SN - 1530-6984

VL - 10

SP - 2461

EP - 2465

JO - Nano Letters

JF - Nano Letters

IS - 7

ER -