Session V16: Nanowires: Electrical and Thermal Properties

8:00 AM–11:00 AM, Thursday, March 18, 2010
Room: B115

Sponsoring Unit: DCMP
Chair: Derek Stewart, Cornell University

Abstract ID: BAPS.2010.MAR.V16.15

Abstract: V16.00015 : Direct measurements of lateral variations of Schottky barrier height across ``end-on'' metal contacts to Si nanowires by ballistic electron emission microscopy

10:48 AM–11:00 AM

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Authors:

  W. Cai
    (The Ohio State Univ.)

  Y. Che
    (The Ohio State Univ.)

  J.P. Pelz
    (The Ohio State Univ.)

  E.R. Hemesath
    (Northwestern Univ.)

  L.J. Lauhon
    (Northwestern Univ.)

Semiconducting nanowires (NWs) are of great interest for future electronic devices, but much needs to be understood about how carrier injection and transport at the contacts are affected by small-size effects [1] and local defects. Here we report measurements of \textit{lateral variations} of the local barrier height across individual ``end-on'' Au Schottky contacts to vertical $\sim $100 nm diameter Si NWs using ballistic electron emission microscopy (BEEM). Vertical Si NWs were grown on Si (111) substrates, embedded in spin-on-glass, and planarized with a chemical mechanical polish. A brief BHF etch and thin Au film deposition were then used to make end-on NW contacts. BEEM measurements show that the local Schottky barrier height (SBH) at the edge of two separate NWs is $\sim $23$\pm $3 meV lower than at the NWs center, most likely due to a stronger local electric field at the contact edge. Electrostatic simulations of a variety of possible mechanisms indicate that positive charge ($\sim $3$\times $10$^{11} \quad e$/cm$^{2})$ near the NW surface (due to near-surface defects or donors) together with geometry-enhanced electric fields effect at the NW edge could produce the stronger local electric field and resulting lower SBH at the contact edge. Work supported by NSF Grant No. DMR-0805237. [1] F. Leonard\textit{ et al}., Phys. Rev. Lett. \textbf{84}, 4693 (2000).

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.V16.15