### Session A12: Directed Organization of Nanostructured Films

8:00 AM–11:00 AM, Monday, March 16, 2009
Room: 308

Chair: Ray Phaneuf, University of Maryland

Abstract ID: BAPS.2009.MAR.A12.5

### Abstract: A12.00005 : Influence of impurities on phase transition in quasi-one-dimensional nanowires on Si surface

9:12 AM–9:24 AM

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#### Authors:

Geunseop Lee
(Inha University, Korea)

Woosang Lee
(Inha University, Korea)

Hyungjoon Shim
(Inha University, Korea)

Sang-Yong Yu
(Korea Research Institute of Standards and Science, Korea)

Ja-Yong Koo
(Korea Research Institute of Standards and Science, Korea)

We investigated using low-energy electron diffraction the influence of impurity doping on the structural phase transition in an array of quasi-one dimensional In nanowires on Si(111). A clean Si(111)4$\times$1-In surface, in its pristine form, undergoes a structural phase transition into a 8$\times$2 phase below 120 K. Introducing various impurities (hydrogen, oxygen, and alkali metals) on the surface at room temperature was found to affect the 4$\times$1-to-8$\times$2 structural phase transition by changing the transition temperature (T$_c$). Adsorption of the two types of the gases affected the transition in opposite ways: hydrogen adsorption lowered the T$_c$, whereas oxygen adsorption raised the T$_c$. Dosing of different alkali metals (Na, K, and Li) all decreased the T$_c$. Usually, impurities are expected to suppress the phase transition into the symmetry-broken phase (the low-temperature phase) by acting as random fluctuations in structure. In this sense, the increase in T$_c$ by the oxygen adsorption is an exceptional case enhancing the phase transition. Possible mechanisms leading to different influences of the various impurities on the structural phase transition of this In/Si(111) will be discussed.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.MAR.A12.5