19-01-2013, 02:55 PM
PRPPERTIES OF SEMICONDUCTOR
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Introduction
Semiconductors are materials whose electrical properties lie between Conductors and Insulators.
Ex : Silicon and Germanium
Semiconductors
Semiconductors are materials that essentially can be conditioned to act as good conductors, or good insulators, or any thing in between.
Common elements such as carbon, silicon, and germanium are semiconductors.
Silicon is the best and most widely used semiconductor.
Extrinsic Semiconductors
Electrical Properties of Semiconductors can be altered drastically by adding minute amounts of suitable impurities to the pure crystals
Impurities: Atoms of the elements different from those forming solid
Interstitial: “foreign” atoms “squeezed” between regular sites crystal sites
Substitutional: “foreign” atoms occupying the sites of host atoms
Intrinsic Semiconductors
Consider nominally pure semiconductor at T = 0 K
There is no electrons in the conduction band
At T > 0 K a small fraction of electrons is thermally excited into the conduction band, “leaving” the same number of holes in the valence band
[attachment=47712]
Introduction
Semiconductors are materials whose electrical properties lie between Conductors and Insulators.
Ex : Silicon and Germanium
Semiconductors
Semiconductors are materials that essentially can be conditioned to act as good conductors, or good insulators, or any thing in between.
Common elements such as carbon, silicon, and germanium are semiconductors.
Silicon is the best and most widely used semiconductor.
Extrinsic Semiconductors
Electrical Properties of Semiconductors can be altered drastically by adding minute amounts of suitable impurities to the pure crystals
Impurities: Atoms of the elements different from those forming solid
Interstitial: “foreign” atoms “squeezed” between regular sites crystal sites
Substitutional: “foreign” atoms occupying the sites of host atoms
Intrinsic Semiconductors
Consider nominally pure semiconductor at T = 0 K
There is no electrons in the conduction band
At T > 0 K a small fraction of electrons is thermally excited into the conduction band, “leaving” the same number of holes in the valence band