Purest semiconductor is known as intrinsic semiconductor. At 0°K, semiconductor behaves like an insulator, because energies of the order of EG cannot be acquired from an electric field. At room temperature, covalent bonds in the semiconductor may be broken into a few Hole–electron pairs, contributing to current flow through the material allowing the conductivity to increase.
With respect to energy, if an electron is given additional energy, it breaks away from its covalent bond. When the free electron enters a Hole in a Valence Band, this excess energy is released as a quantum of heat or light. In turn this quantum of energy may be reabsorbed by another electron to break its covalent bond and create a new Hole–electron pair. Thus Holes and electrons appear to move. The moving charge carries form current. Ohm’s law governs the conduction phenomena in conductors and resistors.
Conduction by Holes is less when compared to that of electrons because of differences in freedom of movements for Holes and electrons, based on their mobility μ. The mobility of electrons μn is greater than the mobility of holes μp because of the differences in relative masses of electrons and Holes.
Typical values of mobility of electrons and Holes in semiconductors
The mobility μ of electrons and Holes is defined as the velocity acquired by these charged particles per unit-applied electric field.
Electrical conduction by electron–Hole pairs generated by thermal energy is called intrinsic conduction in pure semiconductors, of either Silicon or Germanium.