3_1_Module 3 Lecture 2A

3_1_Module 3 Lecture 2A - Recap of Prof. Abidi Lecture...

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Unformatted text preview: Recap of Prof. Abidi Lecture Doping ● Adding special impurities to an intrinsic semiconductor ● N-type: – Add Group V element (extra electron) – Immobilized impurity becomes positive when electron leaves – Increases electron density (orders of magnitude higher) ● P-type – Add Group III element (lacking one electron – extra hole) – Immobilized impurity becomes negative when electron arrives – Doping ● Adding special impurities to an intrinsic semiconductor ● N-type: – Add Group V element (extra electron) – Immobilized impurity becomes positive when electron leaves – Increases electron density (orders of magnitude higher) ● P-type – Add Group III element (lacking one electron – extra hole) – Immobilized impurity becomes negative when electron arrives – Increases hole density (orders of magnitude higher) Carriers How to Use Doped Semiconductors? ● Join together P-type and N-type (carefully!) P-N Junction (Equilibrium) ● You get spontaneous diffusion ● Immobile impurities attract carriers across P-N junction. ● Depletion region where carriers have migrated away. ● But diffusion stops when field created by immobile impurities opposes further carrier movement. ● You essentially have a charged capacitor at the junction (very important in EE115A&B). ● Built-in voltage: V bi ≈ 0.5 – 0.6 V Charged Capacitor??...
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This note was uploaded on 04/04/2010 for the course EE 3 taught by Professor Staff during the Winter '08 term at UCLA.

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3_1_Module 3 Lecture 2A - Recap of Prof. Abidi Lecture...

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