1. UKM Learning and Research Repository
2. PHD Thesis / Tesis PHD
3. Faculty of Science and Technology / Fakulti Sains dan Teknologi

Title:	Physical properties and characterization of CR, NI, CO doped SNO2 SOL gel films annealed in air and nitrogen gas
Authors:	Mohammad Hassan Abdi (P50314)
Supervisor:	Noor Baayah Ibrahim, Associate Prof. Dr.
Keywords:	Physical properties of CR NI CO doped SNO2 SOL gel films Characterization of CR NI CO doped SNO2 SOL gel films CR NI CO doped SNO2 SOL gel films Annealed in air Annealed in nitrogen gas Universiti Kebangsaan Malaysia -- Dissertations
Issue Date:	18-Jul-2014
Description:	Tin oxide is an n-type semiconductor with high transmission and low resistivity. It can be doped with transition metal in order to improve some of its physical properties. Transition metal (Cr, Ni and Co) doped tin oxide thin film with the composition of Sn1-xMxO2 (x=0.00, 0.02, 0.04, 0.06, 0.10, 0.20 and M= Cr, Ni, Co) were prepared by a sol-gel method followed by a spin coating technique. The annealing process was carried out at 600 °C for 2 hours in air. In general, microstructure characterization using X-ray diffractometer (XRD) showed that the Sn1-xMxO2 films were single phase of the tin oxide structure. The lattice parameter and crystallite size of the Sn1-xMxO2 films decreased with the increment of transition metal concentration. The surface morphology was studied using a field emission scanning microscope (FE-SEM). It showed that the film surface were very smooth and dense without crack. The film thickness measured from the film's cross sections images obtained by FE-SEM. The thickness changed as transition metals concentration changed. The particle size was measured by transmission electron microscopy (TEM). The grain size obtained for all samples were between 3.3-6.1nm. The oxidation state of films was examined by X-ray photoelectron spectroscopy (XPS). The obtained binding energy showed that the film contained transition metal, tin and oxygen elements. The electrical property was measured at room temperature (25°C) using Van der Pauw technique. The obtained results showed that tin oxide has the lowest resistivity. The resistivity increased as transition metal increased. The resistivity also increased when the samples were cooled down from 300 to 80 K. The optical property was studied using UV-Vis spectrophotometer. It showed that the transmission of films was high (around 90-98%) and the energy band gap changed between 3.79-3.95 eV as the dopant changed. The characterization using vibrating sample magnetometer (VSM) confirmed that pure and doped tin oxide has magnetic behavior. The origin of magnetization mechanism can be explained by band magnetic polaron (bmp) mechanism. The effect of nitrogen gas annealing was also studied on the samples. It was found that the Sn1-xMxO2 films were tin oxide single phase. However, the intensity of peaks decreased as dopnt increased. The XPS data showed that the peak of nitrogen was very low, meaning that there is a little quantity of nitrogen in the samples. The particle size is bigger and the thickness is thicker than films annealed in air. The interesting results were obtained from the electrical characterization. In general, nitrogen annealing decreased the resistivity of samples and increased the carrier concentration. SnO2 and 2 wt% Ni doped SnO2 samples had semiconductor behavior at 80 – 300 K however 2% wt Cr doped SnO2 and 4% wt Ni doped SnO2 samples had semiconductor property at 200 to 300 K. The samples transmission–were higher and optical band gap were lower than samples annealed in air. All samples had magnetic property at room temperature (25oC). The magnetic saturation of tin oxide annealed in nitrogen enhanced compared to sample annealed in air. In conclusion, annealing in nitrogen produced samples with better physical properties compared to annealing process in air.,PhD
Pages:	160
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.