What is a semiconductor?
A solid-state substance that can be electrically altered. Certain elements in nature, such as silicon, perform like semiconductors when chemically combined with other elements. A semiconductor is halfway between a conductor and an insulator. When charged with electricity or light, semiconductors change their state from nonconductive to conductive or vice versa. The most significant semiconductor is the transistor, which is simply an on / off switch.
A semiconductor is a material that behaves in between a conductor and an insulator. At ambient temperature, it conducts electricity more easily than an insulator, but less readily than a conductor. At very low temperatures, pure or intrinsic semiconductors behave like insulators. At higher temperatures though or under light, intrinsic semiconductors can become conductive. The addition of impurities to a pure semiconductor can also increase its conductivity.
The image to the left shows a silicon semiconductor. Atoms of silicon are stacked perfectly in the form of a crystal into which a small amount of another type of atom is intoduced. In this configuration, each silicon atom shares its outer electrons with its neighbors and their are no free electrons moving about in the crystal due to the silicon atoms. In fact, if there were no other types of atoms in the crystal besides the silicon atoms, the crystal would be an insulator through which currents do not flow under normal circumstances. In N-type semiconductors, other atoms (called impurity atoms) are introduced in the silicon crystal which have an additional outer electron compared to the silicon atom. When they try to fit into the crystal lattice, the extra electron is not shared by the neighboring silicon atoms and it is free to move about. In a P-type semiconductor, the impurity atoms have one fewer electron than the silicon and thus when they try to fit into the lattice, there is a h
A semiconductor is a substance whose electrical conductivity can be altered through variations in temperature, applied fields, concentration of impurities, etc. The most common semiconductor is silicon, which is used predominantly for electronic applications (where electrical currents and voltages are the main inputs and outputs). For optoelectronic applications (where light is one of the inputs or outputs), other semiconductors must be used, including indium gallium phosphide (InGaP), which emits amber and red light, and indium gallium nitride (InGaN), which emits near-UV, blue and green light.
