Demonstrative Video
CURRENT IN SEMICONDUCTORS
Energy band diagram for an unexcited atom of a pure (intrinsic) silicon crystal
No electrons in the conduction band
This condition occurs only at a temperature of absolute 0 Kelvin
Conduction Electrons and Holes
Free electrons are also called conduction electrons
Electron-hole pair is created
Recombination occurs when a conduction-band electron loses energy and falls back into a hole in the valence band.
Electron-hole pairs in a silicon crystal.
Free electrons generated continuously while some recombine with holes.
Electron and Hole Current
Applied voltage attracts thermally generated free electrons in the conduction band towards the positive end
This movement of free electrons is called electron current
In valence band hole current is produced by valence electrons (appear as movement of holes)
The free electrons and holes move in opposite directions