Semiconductor Material:

Semiconductor is a material that has a conductivity level somewhere between the extreme of an insulator and a conductor  

Resistivity of a material is defined as important property of semiconductor material (is that they form a very definite pattern that is period in a nature is single crystal stricture both are tetravalent atom and they form covalent bonding an increase in temperature of a semi conductor can result a in the outermost orbit

Both ge and se Arab  that show a reduction in resistance with increase in temperature of a  semi conductor can result in a substantial increase in a number of free electrons in a material .

Semi conductor material such as that shows a reduction in a resistance with increase in a temperature; are said to have a negative temperature co efficient.