IOSR Journal of Applied Physics (IOSR-JAP) e-ISSN: 2278-4861.Volume 11, Issue 4 Ser. I (Jul. – Aug. 2019), PP 64-69 www.iosrjournals.org DOI: 10.9790/4861-1104016469 www.iosrjournals.org 64 | Page Influence of Li-nitrate doping on the hydrothermally grown ZnO nanorods A. P. Kerasidou 1,* , J. Mageiras 1 , A. Bardakas 1 , V. P. Psycharis 1 & C. Tsamis 1 1 Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, 15310 Athens, Greece *Corresponding Author:A. P. Kerasidou Abstract: Large-scale, dense ZnO nanorods(NRs) are grown on Si(100)/SiO 2 substrates with the assistance of a sol-gel nucleation layer. In this study ZnO NRs are hydrothermally grown by a simple aqueous solution route of Zinc Nitrate Hexahydrate with the addition of lithium nitrate as dopant reagent. The influence of doping concentration and growth duration on the NR morphology was studied in comparison to undoped ZnO NRs grown under the same experimental conditions. It was found that the Li-doped ZnO NRs approached the crystal structure of wurtzite ZnO with well-defined diffraction peaks. The addition of the lithium dopant at 0.5:1, 1:1 and 2:1 ratio to Zinc Nitrate Hexahydrate resulted in an increase of the growth rate (nm/min) in comparison to the undoped NRs. --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 28-06-2019 Date of acceptance: 15-07-2019 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction Zinc oxide (ZnO) (3.37 eV) a representative II –VI compound semiconductor has attracted considerable scientific and technological attention due to its excellent semiconducting, piezoelectric kai pyroelectric [1, 2, 3]properties. It is well known that ZnO is a commonly-used, low-cost, antibacterial [4] material that forms various nanostructures depending on the growth process conditions [5, 6, 7]that can act as building blocks in many applications [8, 9]. Different methods that can be applied in order to synthesize ZnO nanorods (NRs) are chemical vaporand metal organic vapor deposition [10, 11, 12], thermal evaporation [13, 14], electrochemical deposition [15]and the hydrothermal method [1, 16, 17]. The hydrothermal synthesis method, received increased attention for ZnO NRs due to its non-toxic nature, low temperature requirements, low operating cost as also its capability to grow ZnO NRs of various morphologies and dimensions on various substrates [18, 19, 20]. Furthermore, the variations of the process parameters (range of precursors, concentration of reactants, temperature, time etc.) leads to morphological differences in size and shapes for the resulted nanorods [18, 21].The hydrothermal method used to form ZnO NRs,also facilitates the doping (n or p-type) of semiconductor NRswhich is necessary for functional electronic and optoelectronic devices. The doping process of semiconductors with a range of elements is well known to significantly affect their electrical, optical, and magnetic properties [22, 23]. Numerous studies with different kind of doping materials as a donor (to obtain high quality n-type ZnO) or as an acceptor in order to fabricate p-type ZnO, emphasizing the important challenges for ZnO based devices have been reported in the literature [24, 25, 26, 28].The present work reports the synthesis of vertically aligned Li-doped ZnO NRs utilizing hydrothermal growth with lithium nitrate as the dopant source. The influence of Li doping on the growth rate of ZnO nanowires is investigated for various Li to Zn ratios. II. Material and Methods The hydrothermal method applied in this study is solution-basedand consists of a two-step process. The first step is the formation of a nucleation or seeding layer on the substrate surface, and the second step is the hydrothermal growth of the ZnO NRs. The seeding layer can be applied onthe substrate surface, by various film deposition methods [29, 30] or through the coating of the substrate with ZnO nanoparticles. In this study the seeding layer was prepared from a zinc acetate solution and was deposited using spin coating. In particular, zinc acetate solution of 40 mM concentration was prepared by dissolving zinc acetate dihydrate (98%, Aldrich) in ethanol. The prepared mixture was magnetically stirred at 60 o C for 60 minutes to obtain a clear homogeneous solution and left to cool down to room temperature and age for 24 hr. Prior to the spin coating process, Si/SiO 2 (100 nm) substrates were etched by piranha solution (1:1 mixture of concentrated H 2 SO 4 / 30 % H 2 O 2 ) for 20 min, rinsed with deionized (DI) water and dried under N 2 atmosphere. Finally, the prepared solution was spin coated on the Si/SiO 2 substrates at 1000 rpm for 30 s and baked at 500 o C in atmospheric air for 10 min. This coating step has been repeated ten (10) times in order to form the requiredseeding layer. The seeded, with ZnO crystallites, Si/SiO 2 substrates were placed upside down into the growth solution. The growth solution consisted