| AVS 55th International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Wednesday Sessions |
| Session NS+NC-WeA |
| Session: | Nanoscale Devices and Sensors |
| Presenter: | M. Lee, Sandia National Laboratories |
| Authors: | M. Lee, Sandia National Laboratories C. Highstrete, Sandia National Laboratories A.L. Vallett, The Pennsylvania State University S.M. Eichfeld, The Pennsylvania State University J.M. Redwing, The Pennsylvania State University T.S. Mayer, The Pennsylvania State University |
| Correspondent: | Click to Email |
The electrodynamic response of semiconductor nanowires across radio- to microwave frequencies is of great interest to both nanomaterial physics and high-frequency device applications of nanowires. It is of particular interest to highlight differences between nanowire and bulk characteristics of the same nominal material. We present measurements of conductance spectra on undoped, p-type, and n-type silicon nanowire (SiNW) arrays from 0.1 to 50 GHz at temperatures between 4 K and 293 K. Highly crystalline SiNWs were synthesized by VLS growth, assembled into arrays numbering between 11 to >50,000 NWs on co-planar waveguides, and measured using microwave vector network analysis. The complex conductance of all doped SiNW arrays was found to increase with frequency f following a sub-linear power law fs, with 0.3 ≤ s ≤ 0.4, and to agree with the expected Kramers-Kronig relation between real and imaginary parts of the conductance. This frequency dependence was independent of the number of SiNWs, while the conductance magnitude roughly scaled with the the number of SiNWs in the arrays. Such a sub-linear frequency dependent conductance is inconsistent with conventional Drude conductivity seen in bulk doped silicon, but is consistent with behavior found universally in disordered systems, although with an unusually small value of s. The magnitude of the microwave conductance was also observed to be sensitive to exposure to air, with p-type SiNWs becoming more conductive and n-type becoming less conductive upon venting the vacuum test chamber to air. We speculate that probable cause of the inferred disorder arises from Si/SiOx interface states dominating the conduction due to the high surface-to-volume ratio and cylindrical geometry of the nanowires. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. Work at Penn State was supported in part by NSF MRSEC: Center for Nanoscale Science Grant # DMR-0213623, and NSF NIRT Grant # ECCS-0609282.