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Unformatted text preview: D xp o NA 2K S q o ND Vbi NA NA ND NA ND Vbi NAND One-Side Junction ECE 3080 - Dr. Alan Doolittle EE 332 Spring 2013 Qualitative band diagrams with applied voltage: Biased P-N Junction EE 332 Spring 2013 Carrier Flow in Biased Junction Current Flow - Qualitative Zero Bias diffusion drift diffusion Reverse Bias drift Forward Bias VA>0 EE 332 Spring 2013 EE 332 Semiconductor Materials and Devices Lecture 17. Carrier Injection in P-N Junction Diode 1.  2.  3.  Minority carrier injection Diode current I-V characteristics V Bias on P-N Junction Voltageoltage Bias on P-N Junction EE 332 Spring 2013 P-N Junction •  P-n Junction I-V Characteristics I-VPutting it all together Characteristics Putting it all together Forward Bias: Current flow is proportional to e(Va/Vref) due to the exponential decay of carriers into the majority carrier bands Reverse Bias: Current flow is constant due to thermally generated carriers swept out by E-fields in the depletion region Current flow is zero at no applied voltage I=Io(eVa/Vref - 1) Georgia Tech EECE 3080 - Dr. Alan Doolittle E 332 Spring 2013 Assumptions: Quantitative p-n Diode Solution 1) steady state conditions Current Quantitative Diode 2) non- degenerate doping 3) one- dimensional analysis Assumptions: Quasi-Neutral Regions 4) low- level injection 1) steady state conditions 5) no light (GL = 0) 2) non- degenerate doping 3) one- dimensional analysis Current equations: p-type n-type Quasi-Neutral Regions 4) low- level injection J=Jp x (GL 5) no light Jn(x)= 0) Jn =q nnE +qD Current equations:n(dn/dx) J=Jp x Jn(x) Jp = q ppE - qDp (dp/dx) Jn =q Georgia Tech Jp = q nnE +qDn(dn/dx) ppE - qDp (dp/dx) Depletion Region p-type n-type VA Depletion Region VA ECE 3080 - Dr. Alan Doolittle EE 332 Spring 2013 eorgia Tech ECE 3080 - Dr. Alan Doolittle EEqualibrium Carrier Concentrations quilibrium Carrier Concentrations EE 332 Spring 2013 N p the e in depletion t tp 2 tn 2 n x e2xist exist inLexistxistthethe depletion x in nthe depletion in depletion 2 2 ( (nD)p ) ( ( n n) )2 ( ( n p )(region, region, the minoritypn ) ( 0pn )D ( p( 2 pn ) pn pp the region, the minority 2 n P0 n )(2 pn minority DP 0 ( DP np ) n) region, pthe minority 0 N 0 2 2 2 0 DP x 2 0 DN x xp xn p n x x2 n carrier carrier diffusion x diffusion x Minority Carrier Injection carrier diffusioncarrier diffusion n Application of the minority quationdiffusion equation Quantitativedoes carrier SolutionSolution e does not eQuantitative p-n Diode Solution quation Diode Diode equation p-n...
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This document was uploaded on 02/18/2014.

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