OPTOELECTRONICS AND ADVANCED MATERIALS – RAPID COMMUNICATIONS Vol. 3, No. 7, July 2009, p. 693 - 699 Sintering process and annealing effect on some physical properties of V 2 O 5 thin films H. A. MOHAMED a,b a Physics department, faculty of Science, Sohag University, 82524 Sohag, Egypt b Physics department, Teacher's College, King Saud University, 11491 Riyadh, KSA Thin films of vanadium pentoxide (V2O5) on glass substrates were produced by e-beam evaporation technique. The effect of sintering process and annealing temperature on the morphology and optoelectronic properties of these films were studied. The obtained results from scan electron microscope show that, the grain size of V2O5 films increases with increasing both the temperature of sintering and annealing temperature. The as-deposited films show high transmittance in the visible region that decrease with increasing the temperature of annealing. The films that sintered at 500 o C represents the high transmittance value about 85 % in the visible region. The electrical resistivity indicates that, the films that sintered at 400 o C and 600 o C transform from semiconductor to metal at temperature of 250 o C. (Received June 30, 2009; accepted July 20, 2009) Keywords: V 2 O 5 , Thin films, Electrical resistivity, Sintering 1. Introduction Several theoretical and applied studies on Vanadium pentoxide (V 2 O 5 ) materials have been done, due to their industrial importance for many technological applications, such as heterogeneous catalyst [1]. V 2 O 5 plays also the role of active electrode in a rechargeable lithium battery [2], indeed high electrochemical activity, high stability and ease of thin film formation by numerous deposition techniques led to its use as a highly promising intercalation material in solid state microbattery applications. Thin films of vanadium pentoxide can be obtained by different techniques like thermal evaporation [3, 4], pulsed laser deposition [5, 6], d. c. magnetron sputtering [7], r.f. sputtering [8,9], flash evaporation [10, 11], and sol-gel technique [12, 13]. It was found that, their microstructure and composition depend strongly on deposition parameters. It is known that the physical properties of the thin film materials depend on some parameters such as; level and ratio of dopant, substrate temperature, deposition conditions, heat treatment, substrate material, and preparation methods. The sintering process is considered one of the effected parameters which act on the physical properties of thin film materials. Sintering process assist to produce lumps of powder materials in a bulky form without affecting their chemical properties, while their physical properties approach those of single crystal phase [14, 15]. The sintering process is usually carried out in the temperature range M T T 2 M T £ £ where T M is the melting point of the material to be sintered [16]. The aim of this work is to study the influence of sintering process and annealing temperature on the morphological, optical and electrical properties of thin films grown by electron beam evaporation technique from a vanadium pentoxide target. The electron beam evaporation technique offers the following advantages: 1) it has a high power density, and hence a wide range of control over evaporation rates, 2) it is used to evaporate materials which have a high melting point, and 3) it provides economical and efficient usage of evaporants. 2. Experimental details The cold pressing technique was employed to convert the V 2 O 5 powder into tablets form. The sintering process was carried out at three values of temperature of 400 o C, 500 o C, and 600 o C. The time of sintering process was fixed at 5 hours for all samples. The electron beam evaporation was used to deposit the prepared V 2 O 5 tablets into ultrasonically cleaned microscopic glass substrate. Edwards high vacuum ( 2×10 -5 Torr) coating unite model E306A was used to this purpose. The rate of deposition and the thickness of the films were controlled to be about 10 nm min -1 and 90-100 nm, respectively, by means of a digital film thickness monitor model TM200 Maxtek. Optical measurements (transmittance T and reflectance R) were performed using a Jasco V–570 UV–VIS–NIR spectrophotometer in the wavelength range from 200 to 2500 nm at normal incidence. The simple two-probe contacts method was used to measure the electrical resistivity using a Keithley 614 electrometer. The measurements were performed at room temperature. Electrical contacts were made by applying silver paste over the surface of the films with a separation of 3 mm.