Studying the effect of impurities Bi2O3 to SiO2 used in LCD screens

In this study, a liquid crystal display LCD cell was prepared. with the windows made from a thin film of SnO2 add to it Bi2O3 by weight (0,1,3,5,7)% .The effect of adding optical and electrical properties of the cell was studied. The thin film was prepared by vacuum evaporation technique. It was added to use powder mixing technique. The results showed a decrease in the value of the current passing through the cell and an increase in resistance value from 9.7MΩ to 12.5MΩ. The results also showed an increase in the cell's ability to control the light and darkness it with lower voltages by increasing the add rate. This leads to a decrease power used of a single cell. The value of the capacitance is not affected by the addition of Bi2O3 and was stable at ( 3nf ±1% ). Introduction In the early 1970's, digital watches started showing up in the marketplace with a new and different type of display-the liquid crystal display ( LCD) [1] Which is characterized by LED screens with little consumption of current, and the long life in operation [2]. Liquid crystals rotate the optical axis if placed under the influence of a weak electric field[3]. Thin SnO2films can work to connect the current and a window. They are usually used TiO2 as windows. These properties can be improved using some additives for greater transparency and less energy consumption [4]. Plus being cheap, it is easy to manufacture and non-toxic, LCD can be obtained imterms a variety of physical and chemical ways [5]. The purpose of the research is to use windows SnO2 and study the effect of addition Bi2O3 to the electrical and optical properties . Experimental part (SnO2 )1-X(Bi2O3)X thin film Powder technique was used in the process of adding powder of Bi to Sn, where the addition process is done based on weight ratios [6]. Tin and bismuth were used in the form of high purity powder up to 99.9%. Tin was handled as base material (1-X) and Bismuth as an additive for weight x= (0.01,0.03,0.05,0.07)%. After calculating the ratios by a sensitive balance that was mixed using a gate mortar for a period of 30 minutes. The sedimentation was done out of throughout a vacuum evaporation system under vacuum 2.5 X 10 -4 mpa. The weight of 0.004 mg was in a boat of tungsten used for evaporation, which was made by quick evaporation to ensure that no component evaporates before the other. Glass was used as base for deposition. Thin film was oxidized in closed oven with temperature at 350 ° C for 60 minutes .The weighting method represented To calculate thickness of then film, using equation (1)[7] .