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NET ELECTRONICS                           MODULE I

               Figure 1. 83: Various mechanisms of electron-hole recombination in
               semiconductors. (a) Interband transitions (b) Band to localized
               defect states transitions (c) Intraband transitions. ....................... 297

               Figure 1. 84: pn junction LED at (a) equilibrium and (b) forward bias.
                ...................................................................................................... 298

               Figure 1. 85: GaAs based (a) homojunction and (b) heterojunction.
                ...................................................................................................... 299
               Figure 1. 86: Double heterostructure based LED. (a) Device
               structure, with a single pn heterojunctions and a p − p isojunction

               (b) Equilibrium band diagram, with the built-in potential at the pn
               junction (c) In forward bias electrons and holes are injected in the
               Ga ................................................................................................. 300

               Figure 1. 87: Double heterostructure device structure with (a)
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         PravySoft Ezine demo
               surface or (b) edge emission. ........................................................ 302
               Figure 1. 88: Theoretical line width in a LED. ................................ 305
               Figure 1. 89: (a) PL spectrum from a GaAs LED, at two different

               temperatures. (b) Plot of the photon energy vs. temperature ..... 306
               Figure 1. 90: Device structure of an OLED .................................... 314
               Figure 1. 91: Liquid Crystal Phases................................................ 318

               Figure 1. 92: Basic Components of LCD Display ............................ 319
               Figure 1. 93: Transmissive LCD Display Working .......................... 320
               Figure 1. 94: Reflective LCD Display Working ............................... 322
               Figure 1. 95: Positive and Negative LCD Displays ......................... 323

               Figure 1. 96:  Honeycomb pattern of Graphene's atoms .............. 348
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