Photoconduction and the electronic structure of silica nanowires embedded with gold nanoparticles

C.-W. Pao, C.-T. Wu, H.-M. Tsai, Y.-S. Liu, C.-L. Chang, W. F. Pong, J.-W. Chiou, C.-W. Chen, M.-S. Hu, M.-W. Chu, L.-C. Chen, C.-H. Chen, K.-H. Chen, S.-B. Wang, S.-J. Chang, M.-H. Tsai, H.-J. Lin, J.-F. Lee, and J.-H. Guo

Phys. Rev. B 84, 165412 – Published 7 October 2011

Abstract

Silica nanowires (SiO $_{x}$ -NWs) embedded with Au peapods have been studied by energy-filtered scanning transmission electron microscopy (EFTEM), O $K$ - and Au $L_{3}$ -edge x-ray absorption near-edge structure (XANES), and extended x-ray absorption fine structure (EXAFS), x-ray emission spectroscopy (XES) and scanning photoelectron microscopy. XANES and XES data show that band gaps of Au-peapod-embedded and pure SiO $_{x}$ -NWs were 6.8 eV. In additional, XANES and EXAFS results indicate illumination-induced electron transfer from Au peapod to SiO $_{x}$ -NWs and does not show any feature attributable to the formation of Au-Si bonding in the Au peapod embedded in SiO $_{x}$ -NWs with or without illumination. Photoresponse and EFTEM measurements show that green light has more significant enhancement of photoconductivity than red and blue light due to surface plasmon resonance and suggest that transport of electrons across SiO $_{x}$ -NWs is via Mott-variable-range hopping mechanism through localized or defect states.

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Received 25 May 2011

DOI:https://doi.org/10.1103/PhysRevB.84.165412

Authors & Affiliations

C.-W. Pao^1,*, C.-T. Wu², H.-M. Tsai^1,*, Y.-S. Liu¹, C.-L. Chang¹, W. F. Pong^1,†, J.-W. Chiou³, C.-W. Chen², M.-S. Hu⁴, M.-W. Chu⁵, L.-C. Chen^5,‡, C.-H. Chen^4,5, K.-H. Chen^4,5, S.-B. Wang^5,6, S.-J. Chang⁶, M.-H. Tsai⁷, H.-J. Lin⁸, J.-F. Lee⁸, and J.-H. Guo⁹

¹Department of Physics, Tamkang University, Tamsui 251, Taiwan
²Department of Material Science and Engineering, National Taiwan University, Taipei 106, Taiwan
³Department of Applied Physics,National University of Kaohsiung, Kaohsiung 811, Taiwan
⁴Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
⁵Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan
⁶Institute of Microelectronics and Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan
⁷Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
⁸National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan
⁹Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

^*Present address: National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan.
^†wfpong@mail.tku.edu.tw
^‡chenlc@ntu.edu.tw

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Vol. 84, Iss. 16 — 15 October 2011

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