5.76. Electronic Component http://www.ck12.org
less valence electrons than silicon. This is called doping, and it’s what allows the semiconductor to conduct electric
current.
FIGURE 5.162
Q:Why wouldn’t a pure silicon crystal be able to conduct electric current?
A:Electric current is a flow of electrons. All of the valence electrons of silicon atoms in a pure crystal are shared
with other silicon atoms, so they are not free to move and carry current.
There are two different types of semiconductors: n-type and p-type.
- An n-type (negative-type) semiconductor consists of silicon and an element such as phosphorus that gives the
silicon crystal extra electrons. You can see this in theFigure5.162. An n-type semiconductor is like the
negative terminal of a battery. - A p-type (positive-type) semiconductor consists of silicon and an element such as boron that gives the silicon
positively charged “holes” where electrons are missing. This is also shown in theFigure5.162. A p-type
semiconductor is like the positive terminal of a battery.
Diode
A diode is an electronic component that consists of a p-type and an n-type semiconductor placed side by side, as
shown in theFigure5.163. When a diode is connected by leads to a source of voltage, electrons flow from the
n-type to the p-type semiconductor. This is the only direction that electrons can flow in a diode. This makes a diode
useful for changing alternating current to direct current.