ELEC PROPERTIES OF MATERIALS 6 A 3D cubic semiconductor crys

Solution

the electricric properties of a material just check out this if it is correct then take otherwise leave it to explore the electrical properties of materials, i.e. their responses to an applied electric field. We begin with the phenomenon of electrical conduction: the parameters by which it is expressed, the mechanism of conduction by electrons, and how the electron energy band structure of a materialinfluences its ability to conduct. These principles are extended to metals, semiconductors and insulators. Particular attention is given to the dielectric characteristics of insulating materials. The final sections are devoted to the peculiar phenomena of Ferro electricity and piezoelectricity free electron theoryThe electrical conductivity is one of the properties of materials that vary most widely and the best conductors such as copper and silver have values of about 108 -1m -1 and a good insulator such as polystyrene has conductivity 10-15 -1 m -1 . In a metal, the current is carried by conduction electrons, and hence the name electronic conduction. In an isolated atom, the electrons are tightly bound to the nucleus. These electrons are known as core electrons. But there are a few electrons which are loosely bound to the nucleus and are called as valance or conduction electrons which are responsible to the properties of the materials. When the crystal is formed, the valence electrons are treated as electrons of the crystal and do not belong to the individual atom in that crystal. In a crystal, the valence electrons experience an effective potential of all the positive ion cores and is less than that when it experience an effective potential of all positive ion cores and is less than that when it experiences in an isolated atom. A useful assumption can be made here that the effective potential inside the metal is constant and can be considered as zero as a first assumption. This is the fact that at the surface of a metal, the atoms are not completely bonded and there appears the so called surface potential which is much higher than the effective potential. Thus the valance electrons are freely moving in a metal, and it requires certain amount of energy which is more than the surface energy to leave the metal. Thus, the electrons are in potential energy well of depth W as. Remember that we have studied infinite potential well or particle in a rigid box problem in quantum mechanics. The free electron theory of metals is a fundamental theory for understanding the electrical properties.