The CONDUCTION PROCESS in a SEMICONDUCTOR is accomplished by two different types
of current flow: HOLE FLOW and ELECTRON FLOW. Hole flow is very similar to electron flow
except that holes (positive charges) move toward a negative potential and in an opposite direction to that
of the electrons. In an INTRINSIC semiconductor (one which does not contain any impurities), the
number of holes always equals the number of conducting electrons.
DOPING is the process by which small amounts of selected additives, called impurities, are added
to semiconductors to increase their current flow. Semiconductors that undergo this treatment are referred
to as EXTRINSIC SEMICONDUCTORS.
An N-TYPE SEMICONDUCTOR is one that is doped with an N-TYPE or donor impurity (an
impurity that easily loses its extra electron to the semiconductor causing it to have an excess number of