Semiconductor device modeling and characterization ee5342 lecture 10 spring 2011
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Semiconductor Device Modeling and Characterization – EE5342 Lecture 10– Spring 2011. Professor Ronald L. Carter [email protected] http://www.uta.edu/ronc/. First Assignment. e-mail to [email protected] In the body of the message include subscribe EE5342

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Semiconductor device modeling and characterization ee5342 lecture 10 spring 2011

Semiconductor Device Modeling and Characterization – EE5342 Lecture 10– Spring 2011

Professor Ronald L. Carter

[email protected]

http://www.uta.edu/ronc/


First assignment
First Assignment EE5342 Lecture 10– Spring 2011

  • e-mail to [email protected]

    • In the body of the message include subscribe EE5342

  • This will subscribe you to the EE5342 list. Will receive all EE5342 messages

  • If you have any questions, send to [email protected], with EE5342 in subject line.


Second assignment
Second Assignment EE5342 Lecture 10– Spring 2011

  • Submit a signed copy of the document that is posted at

    www.uta.edu/ee/COE%20Ethics%20Statement%20Fall%2007.pdf


Additional university closure means more schedule changes
Additional University Closure Means More Schedule Changes EE5342 Lecture 10– Spring 2011

  • Plan to meet until noon some days in the next few weeks. This way we will make up for the lost time. The first extended class will be Monday, 2/14.

  • The MT changed to Friday 2/18

  • The P1 test changed to Friday 3/11.

  • The P2 test is still Wednesday 4/13

  • The Final is still Wednesday 5/11.


Mt and p1 assignment on friday 2 18 11
MT and P1 Assignment on Friday, 2/18/11 EE5342 Lecture 10– Spring 2011

  • Quizzes and tests are open book

    • must have a legally obtained copy-no Xerox copies.

    • OR one handwritten page of notes.

    • Calculator allowed.

  • A cover sheet will be published by Wednesday, 2/16/11.


Ideal junction theory
Ideal Junction EE5342 Lecture 10– Spring 2011Theory

Assumptions

  • Ex = 0 in the chg neutral reg. (CNR)

  • MB statistics are applicable

  • Neglect gen/rec in depl reg (DR)

  • Low level injections apply so that dnp < ppo for -xpc < x < -xp, and dpn < nno for xn < x < xnc

  • Steady State conditions


q(V EE5342 Lecture 10– Spring 2011bi-Va)

Imref, EFn

Ec

EFN

qVa

EFP

EFi

Imref, EFp

Ev

x

-xpc

-xp

xn

xnc

0

Forward Bias Energy Bands


Law of the junction follow the min carr
Law of the junction EE5342 Lecture 10– Spring 2011(follow the min. carr.)


Law of the EE5342 Lecture 10– Spring 2011junction (cont.)


Law of the junction cont
Law of the EE5342 Lecture 10– Spring 2011junction (cont.)


Injection EE5342 Lecture 10– Spring 2011Conditions


Ideal Junction EE5342 Lecture 10– Spring 2011Theory (cont.)

Apply the Continuity Eqn in CNR


Ideal Junction EE5342 Lecture 10– Spring 2011Theory (cont.)


Ideal Junction EE5342 Lecture 10– Spring 2011Theory (cont.)


Excess minority carrier distr fctn
Excess minority EE5342 Lecture 10– Spring 2011carrier distr fctn


Carrier Injection EE5342 Lecture 10– Spring 2011

ln(carrier conc)

ln Na

ln Nd

ln ni

~Va/Vt

~Va/Vt

ln ni2/Nd

ln ni2/Na

x

xnc

-xpc

-xp

xn

0


Minority carrier currents
Minority carrier EE5342 Lecture 10– Spring 2011currents


Evaluating the EE5342 Lecture 10– Spring 2011diode current


Special cases for EE5342 Lecture 10– Spring 2011the diode current


Ideal diode equation
Ideal diode EE5342 Lecture 10– Spring 2011equation

  • Assumptions:

    • low-level injection

    • Maxwell Boltzman statistics

    • Depletion approximation

    • Neglect gen/rec effects in DR

    • Steady-state solution only

  • Current dens, Jx = Js expd(Va/Vt)

    • where expd(x) = [exp(x) -1]


Ideal diode equation cont
Ideal diode EE5342 Lecture 10– Spring 2011equation (cont.)

  • Js = Js,p + Js,n = hole curr + ele curr

    Js,p = qni2Dp coth(Wn/Lp)/(NdLp) = qni2Dp/(NdWn), Wn << Lp, “short” = qni2Dp/(NdLp), Wn >> Lp, “long”

    Js,n = qni2Dn coth(Wp/Ln)/(NaLn) = qni2Dn/(NaWp), Wp << Ln, “short” = qni2Dn/(NaLn), Wp >> Ln, “long”

    Js,n << Js,p when Na >> Nd


Diffnt’l, one-sided EE5342 Lecture 10– Spring 2011diode conductance

ID

Static (steady-state) diode I-V characteristic

IQ

Va

VQ


Diffnt l one sided diode cond cont
Diffnt’l, one-sided EE5342 Lecture 10– Spring 2011diode cond. (cont.)


Charge distr in a (1- EE5342 Lecture 10– Spring 2011sided) short diode

dpn

  • Assume Nd << Na

  • The sinh (see L12) excess minority carrier distribution becomes linear for Wn << Lp

  • dpn(xn)=pn0expd(Va/Vt)

  • Total chg = Q’p = Q’p = qdpn(xn)Wn/2

Wn = xnc- xn

dpn(xn)

Q’p

x

xn

xnc


Charge distr in a 1- EE5342 Lecture 10– Spring 2011sided short diode

dpn

  • Assume Quasi-static charge distributions

  • Q’p = Q’p = qdpn(xn)Wn/2

  • ddpn(xn) = (W/2)* {dpn(xn,Va+dV) - dpn(xn,Va)}

dpn(xn,Va+dV)

dpn(xn,Va)

dQ’p

Q’p

x

xnc

xn


Cap of a 1 sided short diode cont
Cap. of a (1-sided) EE5342 Lecture 10– Spring 2011short diode (cont.)


General time constant
General time- EE5342 Lecture 10– Spring 2011constant


General time constant cont
General time- EE5342 Lecture 10– Spring 2011constant (cont.)


General time constant cont1
General time- EE5342 Lecture 10– Spring 2011constant (cont.)


References
References EE5342 Lecture 10– Spring 2011

  • *Fundamentals of Semiconductor Theory and Device Physics, by Shyh Wang, Prentice Hall, 1989.

  • **Semiconductor Physics & Devices, by Donald A. Neamen, 2nd ed., Irwin, Chicago.

  • M&K = Device Electronics for Integrated Circuits, 3rd ed., by Richard S. Muller, Theodore I. Kamins, and Mansun Chan, John Wiley and Sons, New York, 2003.

  • 1Device Electronics for Integrated Circuits, 2 ed., by Muller and Kamins, Wiley, New York, 1986.

  • 2Physics of Semiconductor Devices, by S. M. Sze, Wiley, New York, 1981.

  • 3 Physics of Semiconductor Devices, Shur, Prentice-Hall, 1990.


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