Research Article Annealing Heat Treatment of ZnO Nanoparticles Grown on Porous Si Substrate Using Spin-Coating Method K. A. Eswar, 1,2 J. Rouhi, 1 H. F. Husairi, 1,2 M. Rusop, 1,3 and S. Abdullah 1,2 1 NANO-SciTech Centre (NST), Institute of Science, Universiti Teknologi Mara (UiTM), 40450 Shah Alam, Selangor, Malaysia 2 Faculty of Applied Sciences, Universiti Teknologi Mara (UiTM), 40450 Shah Alam, Selangor, Malaysia 3 NANO-Electric Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi Mara (UiTM), 40450 Shah Alam, Selangor, Malaysia Correspondence should be addressed to K. A. Eswar; kevinalvin86@gmail.com Received 20 May 2013; Revised 20 November 2013; Accepted 20 November 2013; Published 4 February 2014 Academic Editor: Jainagesh Sekhar Copyright © 2014 K. A. Eswar et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ZnO nanoparticles were successfully deposited on porous silicon (PSi) substrate using spin-coating method. In order to prepare PSi, electrochemical etching was employed to modify the Si surface. Zinc acetate dihydrate was used as a starting material in ZnO sol- gel solution preparation. Te postannealing treatments were investigated on morphologies and photoluminescence (PL) properties of the ZnO thin flms. Field emission scanning electron microscopy (FESEM) results indicate that the thin flms composed by ZnO nanoparticles were distributed uniformly on PSi. Te average sizes of ZnO nanoparticle increase with increasing annealing temperature. Atomic force microscopic (AFM) analysis reveals that ZnO thin flms annealed at 500 ∘ C had the smoothest surface. PL spectra show two peaks that completely correspond to nanostructured ZnO and PSi. Tese fndings indicate that the ZnO nanostructures grown on PSi are promising for application as light emitting devices. 1. Introduction In the past decade, developing high-quality semiconduc- tor nanostructures has attracted increasing attention due to promising applications in electronic and optoelectronic devices arising from their physical properties. ZnO is a wide band gap semiconductor with excellent chemical stability and high exciton binding energy [1]. Tese properties make it widely used in optoelectronic devices such as solar cells, gas sensor, UV sensor, LED applications, and so on [2–6]. In order to synthesis ZnO, various methods were applied such as laser deposition [4], RF magnetron sputtering [3, 5], mist- atomization [7], and sol-gel deposition [2, 6, 8, 9]. High quality ZnO nanostructures were obtained by very expensive and complicated equipment [10]. However, expen- sive and complicated equipments for ZnO synthesization are not applicable in large scale productions. In this work, ZnO thin flm was deposited by sol-gel spin coating. Tis simple method is using less expensive equipment and easy to handle compared to other technique. So, this low-cost technique becomes more promising in bulk productions. Other than that, substrate selection is very important to ZnO thin flm properties. Physical, optical, and electrical properties of ZnO will be diferent using diferent substrates. Suresh Kumar et al. have studied the deposition of ZnO nanostructure on indium-tin oxide (ITO), glass and poly- ethylene terephthalate polymer (PET) substrates [11]. Tey found that diferent substrates will produce diferent type of ZnO nanostructures. Besides, substrate selections are also based on its device application. Mamat et al. have fabricated UV photoconductive sensors on glass substrate [12] and Gao et al. have deposited ZnO flms on silicon wafer in order to study the optical properties for solar cells applications. Besides, Yang et al. suggested that white light emitting diode can be produced by depositing ZnO flms on PSi substrate [5]. In this work, PSi substrate was prepared by modifying the silicon wafer surface using electrochemical anodization method. Kim et al. suggested that modifcation of silicon Hindawi Publishing Corporation Advances in Materials Science and Engineering Volume 2014, Article ID 796759, 6 pages http://dx.doi.org/10.1155/2014/796759