When a semiconductor is in a higher temperature environment

When a semiconductor is in a higher temperature environment, its conductivity of electricity improves but if it gets heated up too much, the conductivity would reach a maximum then start to decrease. On the other hand, when a metal gets warmer its conductivity decreases. Explain what causes the difference in these material observations Ceramic pillars are often used to separate electrical wires from each other on high voltage lines, what do you think the advantages of using ceramics to insulate high voltage as opposed to a polymer? Explain why it is better to use a glass like silica to insulate high voltage rather than something like a window glass (soda lime silica)

Solution

1)--Conductivity is a function of number of free charge Carriers and their mobility. Metals are already having maximum number of free charge Carriers when temperature goes up there mobility decreases and hence the conductivity. In semiconductors with the increasing temperature number of Freecharge career increase hence conductivity increases but at a very high temperature the number of free charge carrier reaches its maximum and after that the mobility starts decreasing hence conductivity decrease.

2)-- Up to 1960 glass insulators was widely used ,from 1960 the use of ceramic insulator becomes popular. Ceramic insulators have excellent properties to be used as an insulator , it has excellent strength because they are rich in Alumina they also have high dielectric strength. Where as Polymers are light in weight and excellent hydrophobic capabilities they are ideal to use in polluted areas but Polymers as an insulator has to prove its long term service life like glass and porcelain like ceramic.

3)-- both the silica and the soda lima belongs to same family of material still they have some differences. Glass made from pure silica is durable strong and have high melting point which command its use have and insulators while soda lime glass have low melting point because of the material added to it this edition increase its workability at the cost of toughness thermal stability hence it is not suitable to use as an insulator.