What is hole flow

An electron hole is one of the two types of charge carriers that are responsible for creating electric current in semiconducting materials. A hole can be seen as the "opposite" of an electron.

Unlike an electron which has a negative charge, holes have a positive charge that is equal in magnitude but opposite in polarity to the charge an electron has. Holes can sometimes be confusing as they are not physical particles in the way that electrons are, rather they are the absence of an electron in an atom.

Holes can move from atom to atom in semiconducting materials as electrons leave their positions. Imagine people standing in a line, on a set of steps. If the person at the front of the line goes up one step, that person leaves a hole. As everyone steps up one step the available step the hole moves down the steps. Holes are formed when electrons in atoms move out of the valence band the outermost shell of the atom that is completely filled with electrons into the conduction band the area in an atom where electrons can escape easily , which happens everywhere in a semiconductor.

In order to encourage hole formation semiconductors are doped with certain elements. These semiconductors, where holes are the most prominent charge carrier, are known as p-type. This hole is then filled by the ball number 2, which leaves still another hole. Ball number 3 then moves into the hole left by ball number 2.

This causes still another hole to appear where ball 3 was. Notice the holes are moving to the left side of the plank. This action continues until all the balls have moved one space to the right in which time the hole moved four spaces to the left and came to rest at the left-hand end of the plank.

In the theory just described, two current carriers were created by the breaking of covalent bonds: the negative electron and the positive hole.

These carriers are referred to as electron-hole pairs. Since the semiconductor we have been discussing contains no impurities, the number of holes in the electron-hole pairs is always equal to the number of conduction electrons. Another way of describing this condition where no impurities exist is by saying the semiconductor is intrinsic. The term intrinsic is also used to distinguish the pure semiconductor that we have been working with from one containing impurities.

Anyone interested in using this applet in connection with any published paper or commercial venture should please first consult the author.

Thank you. Hole Flow In a sense, there really is something that moves from positive to negative while the electrons are moving the other way. Back to Lisa's Java Applets Overview page. Back to Lisa's Academic Activities page. Back to Lisa's home page, Over the Rainbow. Send Lisa email.