ORIGINAL PAPER Novel photoconductive Ag/nanostructure ruthenium oxide/p-type silicon Schottky barrier diode by sol–gel method Ahmed A. Al-Ghamdi • Attieh A. Al-Ghamdi • Omar A. Al-Hartomy • Ahmed M. Nawar • E. El-Gazzar • Farid El-Tantawy • F. Yakuphanoglu Received: 27 April 2013 / Accepted: 8 June 2013 / Published online: 22 June 2013 Ó Springer Science+Business Media New York 2013 Abstract A new Schottky photodiode of Ag/RuO 2 /p-Si/ Al was successfully fabricated using spin-coating tech- nique. The ruthenium oxide (RuO 2 ) nanoparticles with an average size of 8 nm were synthesized using a sol–gel method. The crystal structure and morphology of the syn- thesized RuO 2 were analyzed by means of X-ray diffrac- tion, energy dispersive X-ray spectroscopy, transmission electron microscopy and selective area electron diffraction. The rectification ratio of the diode was found to be 112 at ±2 V. The ideality factor and barrier height values of the Ag/RuO 2 /p-Si/Al diode were obtained to be 1.47 and 0.55 eV, respectively. The Cheung–Cheung and Norde’s models were used to determine the diode parameters. The photoresponse behavior of the fabricated Ag/RuO 2 /p-Si/Al diode was studied under various illumination intensities. The transient photocurrent results indicate that photocur- rent under illumination is higher than the dark current and this indicates that the fabricated diode behaves as a pho- todiode. The capacitance–voltage–frequency measure- ments indicate that the capacitance of the diode depends on voltage and frequency. The obtained results suggest that the new Ag/RuO 2 /p-Si/Al diode can be used an optical switching device for optical sensor applications and are also expected to be generated in the future study. Keywords Ruthenium oxide nanoparticles  Schottky photodiode  Sol–gel 1 Introduction This study is part of an on-going research project aiming to develop high performance nanostructure metal oxides for photodiode with high efficiency and good stability. Nano- scale materials, due to their diverse electronic and optical properties, and with a range of architectures, are constantly being explored for an array of low-cost, sensitive, and scalable photodetection technologies [1–3]. Alternative low-loss materials, such as conducting oxide films, are potentially advantageous for many plasmonic applications, since they exhibit both a small negative real permittivity and relatively small losses in the near infrared [4–7]. In fact, conducting oxide materials have much lower free charge carrier concentrations (10 20-22 cm -3 ) as compared to met- als ( [ 10 23 cm -3 )[8, 9]. This makes their plasma frequen- cies smaller and hence their imaginary permittivity and losses lower than those of metals, making them suitable for transformation optics such as photodetectors [10, 11]. In particular, ruthenium oxide is considered one of the most important metal-oxides because of its high reactivity with reducing agents due to its oxidizing properties, low resis- tivity (*35 lX cm at room temperature), good thermal A. A. Al-Ghamdi  O. A. Al-Hartomy  F. Yakuphanoglu Department of Physics, Faculty of Sciences, King Abdulaziz University, Jeddah, Saudi Arabia A. A. Al-Ghamdi Department of Physics, Faculty of Science, King Abdulaziz University, North Campus, Jeddah, Saudi Arabia O. A. Al-Hartomy Department of Physics, Faculty of Science, Tabuk University, Tabuk 71491, Saudi Arabia A. M. Nawar  E. El-Gazzar  F. El-Tantawy Department of Physics, Faculty of Science, Suez Canal University, Ismailia, Egypt F. Yakuphanoglu (&) Department of Physics, Faculty of Science, Firat University, 23119 Elazig, Turkey e-mail: fyhan@hotmail.com; fyhanoglu@firat.edu.tr 123 J Sol-Gel Sci Technol (2013) 67:368–375 DOI 10.1007/s10971-013-3090-x