Lecture2a - Diode current also follows the exponential...

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Lecture 2. PHYSICS OF DIODES Objectives: Understand construction of a p-n junction diode Describe types of bias Describe operation principle of different diode types Topics: p-n junction, forward and reverse bias V-I characteristics of a p-n junction diodes Zener diode, photodiode, LED
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P-N Junction Diode - metallurgical bond of 2 types of materials (p- and n-) P – type (increased h + concentration) N – type (increased e - concentration) Does it mean we have current?
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P-N Junction Diode Biasing a) FORWARD BIAS Extra carriers neutralize ions depletion region vanishes b) REVERSE BIAS Diode conducts current Extra carriers widen depletion region No current is conducted
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V-I Characteristics of a P-N Junction Diode Apply voltage – find current Current depends on carrier concentrations
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V-I Characteristics of a P-N Junction Diode (cont’d) When an external source is attached to the diode, carrier concentrations are related exponentially to the applied voltage (see previous slide)
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Unformatted text preview: Diode current also follows the exponential equation In the forward-biased region current equation could be simplified Turn-on voltage V f : Zener Diode- very similar to a regular diode, but heavily doped a) Forward-biased condition b) Reverse-biased condition Zeners are primarily used in the reverse-biased configuration Photodiode- have exposed pn-junction- used in the reverse-biased configuration no light = no current light = additional e-- h + pairs created in the depletion region current generated In the forward-biased region: Light-Emitting Diode (LED)- provides the inverse function of the photodiode- used in the forward-biased configuration Electrons and holes are injected by the voltage source in opposite directions across the depletion region Optical output power: Diode current follows the usual equation Efficiency...
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Lecture2a - Diode current also follows the exponential...

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