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Semiconductor Device Modeling and Characterization EE5342, Lecture 10 -Sp 2002

Semiconductor Device Modeling and Characterization EE5342, Lecture 10 -Sp 2002. Professor Ronald L. Carter ronc@uta.edu http://www.uta.edu/ronc/. SPICE Diode Static Model. V ext = v D + i D *RS. Dinj IS N ~ 1 IKF, VKF, N ~ 1 Drec ISR NR ~ 2. i D *RS. V d.

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Semiconductor Device Modeling and Characterization EE5342, Lecture 10 -Sp 2002

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  1. Semiconductor Device Modeling and CharacterizationEE5342, Lecture 10 -Sp 2002 Professor Ronald L. Carter ronc@uta.edu http://www.uta.edu/ronc/

  2. SPICE DiodeStatic Model Vext = vD + iD*RS • Dinj • IS • N ~ 1 • IKF, VKF, N ~ 1 • Drec • ISR • NR ~ 2 iD*RS Vd

  3. SPICE DiodeStatic Model Eqns. Id = area(Ifwd - Irev) Ifwd = InrmKinj + IrecKgen Inrm = IS{exp [Vd/(NVt)] - 1} Kinj = high-injection factorFor IKF > 0, Kinj = IKF/[IKF+Inrm)]1/2 otherwise, Kinj = 1 Irec = ISR{exp [Vd/(NR·Vt)] - 1} Kgen = ((1 - Vd/VJ)2 + 0.005)M/2

  4. Interpreting a plotof log(iD) vs. Vd In the region where Irec < Inrm < IKF, and iD*RS << Vd. iD ~ Inrm = IS(exp (Vd/(NVt)) - 1) For N = 1 and Vt = 25.852 mV, the slope of the plot of log(iD) vs. Vd is evaluated as {dlog(iD)/dVd} = log (e)/(NVt) = 16.799 decades/V = 1decade/59.526mV

  5. Static Model Eqns.Parameter Extraction In the region where Irec < Inrm < IKF, and iD*RS << Vd. iD ~ Inrm = IS(exp (Vd/(NVt)) - 1) {diD/dVd}/iD = d[ln(iD)]/dVd = 1/(NVt) so N ~ {dVd/d[ln(iD)]}/Vt = Neff, and ln(IS) ~ ln(iD) - Vd/(NVt) =ln(ISeff). Note: iD, Vt, etc., are normalized to 1A, 1V, resp.

  6. Static Model Eqns.Parameter Extraction In the region where Irec > Inrm, and iD*RS << Vd. iD ~ Irec = ISR(exp (Vd/(NRVt)) - 1) {diD/dVd}/iD = d[ln(iD)]/dVd ~ 1/(NRVt) so NR ~ {dVd/d[ln(iD)]}/Vt = Neff, & ln(ISR) ~ln(iD) -Vd/(NRVt)= ln(ISReff). Note: iD, Vt, etc., are normalized to 1A, 1V, resp.

  7. Static Model Eqns.Parameter Extraction In the region where IKF > Inrm, and iD*RS << Vd. iD ~ [ISIKF]1/2(exp (Vd/(2NVt)) - 1) {diD/dVd}/iD = d[ln(iD)]/dVd ~ (2NVt)-1 so 2N ~ {dVd/d[ln(iD)]}/Vt = 2Neff, and ln(iD) -Vd/(NRVt)=ln(ISIKFeff). Note: iD, Vt, etc., are normalized to 1A, 1V, resp.

  8. Static Model Eqns.Parameter Extraction In the region where iD*RS >> Vd. diD/Vd ~ 1/RSeff dVd/diD = RSeff

  9. Getting Diode Data forParameter Extraction • The model used .model Dbreak D( Is=1e-13 N=1 Rs=.5 Ikf=5m Isr=.11n Nr=2) • Analysis has V1 swept, and IPRINT has V1 swept • iD, Vd data in Output

  10. diD/dVd - Numerical Differentiation

  11. dln(iD)/dVd - Numerical Differentiation

  12. Diode Par.Extraction 1/Reff iD ISeff

  13. Results ofParameter Extraction • At Vd = 0.2 V, NReff = 1.97, ISReff = 8.99E-11 A. • At Vd = 0.515 V, Neff = 1.01, ISeff = 1.35 E-13 A. • At Vd = 0.9 V, RSeff = 0.725 Ohm • Compare to .model Dbreak D( Is=1e-13 N=1 Rs=.5 Ikf=5m Isr=.11n Nr=2)

  14. Hints for RS and NFparameter extraction In the region where vD > VKF. Defining vD = vDext - iD*RS and IHLI = [ISIKF]1/2. iD = IHLIexp (vD/2NVt) + ISRexp (vD/NRVt) diD/diD = 1  (iD/2NVt)(dvDext/diD - RS) + … Thus, for vD > VKF (highest voltages only) • plot iD-1vs. (dvDext/diD) to get a line with • slope = (2NVt)-1, intercept = - RS/(2NVt)

  15. Application of RS tolower current data In the region where vD < VKF. We still have vD = vDext - iD*RS and since. iD = ISexp (vD/NVt) + ISRexp (vD/NRVt) • Try applying the derivatives for methods described to the variables iD and vD (using RS and vDext). • You also might try comparing t0he N value from the regular N extraction procedure to the value from the previous slide.

  16. Project 2 • A set of iD vs. Vd (> 0) data will be given. • Develop a method (more accurate than in this presentation) for extracting the parameters IS, N, ISR, NR, IKF and RS • Document your extraction methods and the values you have extracted. • Compare a SPICE diode simulation obtained with the extracted values to the data given originally. • Calculate a net error of your simulation relative to the data originally given

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