Lec2.1 - N(Negative type one more electron in the valence...

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EE 330 –Diodes, Chapter 3 Sedra and Smith All matters in nature have electrical properties: Groups: Conductors: Most metals (aluminum, copper...) some ceramics show superconductivity at low temp Insulators: Plastic, and most ceramics Semiconductors: Silicon (element 14), GaAs (Gallium Arsenide) Needs controlled addition of impurity Concept: Electric conduction requires free spaces in the valence energy band of an atom. Conduction band : the unfilled energy levels into which electrons can be excited to become conductive electrons; a band that when partially occupied by mobile electrons, permits their net movement in a particular direction, producing the flow of electricity through the solid. Intrinsic Semiconductor: Essentially Pure Extrinsic Semiconductor: Has added impurity. (Doped) Crystal : a solid composed of atoms, ions, or molecules arranged in an orderly pattern that is repeated in three dimensions.
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Doping: The process of adding impurity (i.e. Arsenic, Aluminum) to semiconductor. Types:
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Unformatted text preview: N (Negative type) one more electron in the valence band. The extra electron is available to carry current. P (Positive type) one less electron in the valence band. The extra hole is available to carry current. P-N junction : a boundary between p-type and n-type regions within a single crystal of a semiconductor material, a diode. When the two materials are placed together, electrons from the n-side combine with the holes on the p-side. This results in a positive charge on the n-side of the junction and a negative charge accumulation on the p-side. This separation of charge creates a junction potential. Note: There are no electrons or holes at the junction, they have combined with each other. A p-n junction under forward and reverse bias. Notice that in forward bias, the barrier is lowered, while in reverse bias, the barrier is raised. Diode : a two-electrode semiconductor device that utilizes the rectifying properties of a p-n junction or a point contact....
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