10 - at T>0 K .) (2). For a metal, there are...

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1 Lu ECE331 Kronig-Penney Model The 1-D potential function can be simplified as a series of potential barriers with an identical barrier width and period. Lu ECE331 E-K Diagram in Kronig-Penney Model To have solutions, we have energy bands and gaps.
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2 Lu ECE331 Simplified Band Diagrams The top of the valence band and the bottom of the conduction band are similar parabolic functions. Lu ECE331 Insulators, Semiconductors, Metals Simplified band structures of insulators, semiconductors, and metals at 0 K .
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3 Lu ECE331 Insulators, Semiconductors, Metals (1). For a semiconductor, Eg is small enough that a significant number of electrons can be excited across the energy gap by irradiation. (e.g. there are significant number of electrons
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Unformatted text preview: at T>0 K .) (2). For a metal, there are large number of electrons even at 0K. (3). For a metal, electrons can move freely under an electric field. Lu ECE331 Direct and Indirect Semiconductors 4 Lu ECE331 Direct and Indirect Semiconductors (1). Typical direct semiconductors: GaAs, InP, GaN. (2). Typical indirect semiconductors: Si, Ge, AlAs. (3). For an optical emission to occur: (a)An electron must be at an elevated energy state. (b) There must be an empty state at a lower energy for electron to go to; (c)Energy must be conserved; (d)K must be conserved. Lu ECE331 Variation of energy bands with alloy composition...
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This note was uploaded on 04/09/2010 for the course ECE 331 taught by Professor Rajan during the Spring '09 term at Ohio State.

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10 - at T>0 K .) (2). For a metal, there are...

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