lead (Pb) slight films were deposited into clean glass substrate using a very simple technique of single source resistive heating Vacuum Evaporation at a pressure of about 8x106 torr. The deposition rate was 1.57nms-1. The electrical properties were measured for both as-deposited and annealed films. The temperature dependence of resistivity and the temperature coefficient of resistivity (T.C.R.) have been measured. It has been found that the resistivity increases with the increase of temperature for both types of films. In both the cases, T. C. R. was found to be positive indicating metallic behavior. The activation energy and grain size of the film are evaluated. The thickness dependence of resistivity has been investigated and it is found that the resistivity increases with the decrease of film thickness. The effect of pressure on resistivity has also been carried out.
The film resistivity can be influenced by adsorption and deposition as well as by incorporation and degassing of residual gas molecules during the evaporation and subsequent heating and cooling cycle. Therefore, high vacuum conditions are essential. The lead (Pb) films are deposited by vacuum evaporation techniques. The atoms are condensed from the vapor phase into a clean glass substrate. Deposition of lead (Pb) slight films in such a process is achieved by one or more phase transformation of slight films. Slight films exhibits different electrical, optical, mechanical, structural and magnetic properties than their corresponding bulk bodies.
Theoretical explanations regarding the properties of slight films were required vigorously. In 1901, Thomson first proposed the size effect theory to explain the high electrical resistivity of the film specimen compared to that of the bulk material. For spherical fermi-surface and free electron model, the size effect theory was explained by Fuchs in 1938 and afterrwards in 1950 by Sondheimer to include galvanometric effect. The size effect theory for T.C.R. was computed by Campbell in 1966 for metal films. The most modern development in the field of slight film physics has been possible using the optoelectronics devices. Slight film microelectronics has emerged in the field of electronics and consequently a rapid development has occurred in microelectronics industry throughout the world.
In the present work, interest is focused on the effect of temperature and thickness on electrical properties such as resistivity, T.C.R., activation energy, grain size etc. of leads (Pb) slight films. The temperature and thickness vary from 303°K-433°K and 106nm – 229nm respectively. All the films have been found to be metallic in nature. The variations of electrical properties as a function of temperature (303°K- 433°K) and thickness (106nm – 229nm) have been explained. Measurements have been made on both the as-deposited and annealed films. The resistivity was found to be in the order of 10-5 ohm-cm.
