CHM 114 Lecture Notes - Lecture 26: Valence Electron, Fermi Level, Dopant
Document Summary
For electrons in a band to conduct . Electrons in a metal are mobile because the energy gap between the lumo and homo is infinitesimally small in the band. Semiconductors comparison of si, ge and c. Group iv solids all have 4n valence electrons. Effect of t on the electrical conductivity of metals and semiconductors. With increasing t, the electrical conductivity of a semiconductor increases while that of a metal decreases. Mobility of electron in semiconductors is strongly affected by temperature. No electrons can be above the valence band at 0k, since none have energy above the fermi level and there are no available energy states in the band gap. At high temperatures, some electrons can reach the conduction band and contribute to electric current. At room temperature si & ge (group iv element) not very useful with electrical devices (tiny currents) The 5-valent dopant (p in this case) has one more valence electron than si.