book of abstracts - IM2NP

A B S T R A C T S MONDAY, JUNE 28 N A N O S E A 2 0 1 0
Room Calendal
10h30-11h10
Nanoscale phase transitions and nanowire growth.
J. Tersoff (IBM Watson Research Center Yorktown Heights NY 10598 USA)
Semiconductor nanowires can be readily grown from tiny catalyst particles. These wires, with diameters as
small as a few nanometers, have attracted intense interest due to their potential applications in nanoscale
technologies. At the same time, they offer a unique opportunity to deepen our understanding of crystal
growth. It has long been realized that novel effects are expected for growth at the nanoscale. But only
recently has it become possible to measure these effects directly, using in-situ microscopy.
This talk will describe some recent progress in understanding growth at the nanoscale, by combining
experimental observations, theoretical modeling, and direct computer simulation of nanowire growth [1-3].
We studied the sequence of phase transformations as a Au seed particle is exposed to disilane to initiate
nanowire growth. On an inert substrate and above the eutectic temperature, the system progresses from Au
to a two-phase Au+AuSi eutectic system, to liquid AuSi, and finally to AuSi+Si, initiating nanowire growth
[2,3]. By comparing the experimental measurements with a simple theoretical model, we determine the
changes in the equilibrium phase diagram for nanoscale systems, and the effect of system size on the
nucleation process. We also find dramatic deviations from equilibrium due to kinetic effects in nanowire
growth. We have developed a theoretical model for the eutectic system evolution, allowing direct computer
simulation of nanowire growth [3]. These simulations shed light on how material properties and growth
conditions control the wire morphology and growth stability [3].
* Work done in collaboration with K.W. Schwarz, B.J. Kim, S. Kodambaka, E.A. Stach, and F.M. Ross.
[1] B. J. Kim, J. Tersoff, S. Kodambaka, M. C. Reuter, E. A. Stach, and F. M. Ross, Science 322, 1070 (2008).
[2] K. W. Schwarz and J. Tersoff, Phys. Rev. Lett. 102, 206101 (2009).
[3] B. J. Kim, J. Tersoff, C.-Y. Wen, M. C. Reuter, E. A. Stach, and F. M. Ross, Phys. Rev. Lett. 103, 155701 (2009)
11h10-11h30
Microstructure and compositional study of MBE grown ZnSe NWs with
CdSe inclusions.
S. Tatarenko (Nanophysics and Semiconductors Group, INAC and Institut NEEL, CEA/CNRS/University
Joseph Fourier, France) serge.tatarenko@grenoble.cnrs.fr
We have recently shown that a single CdSe quantum dot embedded in a ZnSe nanowire (NW) is an efficient
single photon source operating at a temperature as high as 220K [1]. However, when grown on an oxidized
Si (001) substrate in the VLS growth mode catalyzed by gold particles, the NWs present a random
distribution of orientations and densities.
In this contribution we report on the epitaxial growth of ZnSe/CdSe NWs on 2D epitaxial ZnSe (100) on
GaAs (100) substrate. Scanning electron microscopy (SEM) and High Resolution Transmission Electron
Microscopy (HRTEM) images (Fig 1) show ZnSe NWs with hexagonal wurtzite structure along the [0001]
axis and also NWs with cubic zinc-blende structure along the [100] axis. The presence of different NW
orientations is attributed in part to the formation of [110] oriented nanotrenches generated by Au dewetting
at 530°C [2, 3]. The first steps of the growth for both growth directions will be presented in details as well
as the influence of the growth parameters.
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