IOSR Journal of Applied Physics (IOSR-JAP) e-ISSN: 2278-4861.Volume 8, Issue 2 Ver. I (Mar. - Apr. 2016), PP 110-113 www.iosrjournals.org DOI: 10.9790/4861-080201110113 www.iosrjournals.org 110 | Page Hydrothermal Growth of ZnO Nanostructures on Seed Layer Coated Substrates and their Characterization Shrisha B. V., Shashidhara Bhat., Parvathy Venu M., K Gopalakrishna Naik. Department of Studies in Physics, Mangalore University, Mangalagangotri – 574199, India Abstract : Zinc Oxide (ZnO) nanostructures were grown on ZnO seed layer deposited glass, ITO coated glass, quartz and p-silicon (p-Si) substrates by hydrothermal method. The structural, morphological and optical properties of the grown ZnO nanostructures were characterized by XRD, FESEM and UV-visible spectroscopy. The elemental compositions of the samples were investigated by EDS. Keywords: ZnO, Nanostructures, Spincoat, Hydrothermal. I. Introduction Nanostructured materials have received a special attention in many fields because of its unique physical, chemical and electrical properties which furnish them suitable for potential applications in optoelectronic devices, optics, photonics, medicine, and other fields [1]. When the size of a material reduces to the nanoscale, change in size dependent properties are often observed. This is mainly due to: (i) large fraction of surface atoms; (ii) high surface energy; (iii) spatial confinement of the carriers; (iv) reduction of imperfections in the nanometer size materials [2]. Among the various semiconductor nanostructure materials, the studies on ZnO nanostructures find special interest due to their applications in nanoelectronics and optoelectronics. ZnO has a bulk band gap of about 3.37 eV and large exciton binding energy of 60 meV at room temperature also find potential applications like in gas sensors, biosensors, solar cells, piezoelectric devices etc. [3]. The methods such as pulsed laser deposition, molecular beam epitaxy, metal organic chemical vapor deposition, hydrothermal, and electrochemical method have been used for growth of ZnO nanostructures [4]. Among these methods, hydrothermal technique has become a promising option because of its simplicity, low cost, environment friendly and high efficiency [5]. In the present work, ZnO nanostructures were grown on ZnO seed layer coated glass, ITO coated glass, quartz and p-Si substrates by hydrothermal method. The ZnO seed layers were deposited on the above substrates by sol-gel spin coat method. II. Experimental The growth of ZnO nanostructures on glass, quartz, ITO coated glass and p-Si substrates was carried out in two steps. In the first step, the ZnO seed layers were deposited on glass, quartz, ITO coated glass and p-Si substrates by a sol-gel spincoat method. Prior to deposition, the substrates were rinsed in distilled water and cleaned ultrasonically in ethanol and then in acetone for removing organic impurities. Zinc acetate dihydrate [Zn(CH 3 COO) 2 .2H 2 O] was dissolved in a mixture of 2-methoxyethanol (C 3 H 8 O 2 ) and monoethanolamine (MEA, C 2 H 7 NO) which served as the solvent and stabilizer, respectively. The concentration of zinc acetate was maintained at 1 M and the molar ratio of MEA to zinc acetate was maintained at 1.0. The resultant solution was stirred at 60 ◦ C for 4 h and then aged for 48 h. The prepared solution was then deposited on the substrates using the spin-coating technique at 3000 rpm for 30 s. The as-deposited films were immediately placed in a furnace which is maintained at 300 ◦ C and kept for 10 min. The deposition and preheating processes were repeated for 4 times in order to get ZnO seed layer of desired thickness. Thereafter, the ZnO seed layer coated substrates were heated at 400 ◦ C in ambient condition using a furnace for 1 h and then cooled to room temperature. This thermal treatment process is necessary to in order to improve the adhesion of the seeded ZnO particles with the substrate. Higher the temperature, larger the size of the ZnO seed crystal which results in the formation of ZnO nanostructures with bigger size. Therefore thickness and crystal size of the ZnO seed layers will affect the quality of the grown ZnO nanostructures. After preparing the ZnO seed layers, a typical hydrothermal synthesis of ZnO nanostructures was carried out by immersing the ZnO seed layer coated substrates in equi molar solution (0.1 M) of zinc nitrate hexahydrate [Zn(NO 3 ) 2 .6H 2 O] and hexamethylenetetramine (HMT, C 6 H 12 N 4 ,) taken in a teflon-lined stainless steel autoclave of 60 mL capacity. HMT is the most commonly used reagent which acts as a pH buffer reagent. The growth was carried out at 90 ◦ C for 6 h. After that autoclave was allowed to cool to room temperature, the samples were removed, rinsed in distilled water and dried in air. The structural and morphological properties of the as grown ZnO nanostructures were investigated using X-ray diffraction (RIGAKU smart lab X-ray