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# Semiconductor Device Modeling and Characterization EE5342, Lecture 9-Spring 2003 PowerPoint PPT Presentation

Semiconductor Device Modeling and Characterization EE5342, Lecture 9-Spring 2003. Professor Ronald L. Carter ronc@uta.edu http://www.uta.edu/ronc/. SPICE Diode Static Model Eqns. Id = area  (Ifwd - Irev) Ifwd = Inrm  Kinj + Irec  Kgen Inrm = IS  { exp [Vd/(N  Vt)] - 1}

Semiconductor Device Modeling and Characterization EE5342, Lecture 9-Spring 2003

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## Semiconductor Device Modeling and CharacterizationEE5342, Lecture 9-Spring 2003

Professor Ronald L. Carter

ronc@uta.edu

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

### 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)]1/2otherwise, Kinj = 1

Irec = ISR{exp [Vd/(NR·Vt)] - 1}

Kgen = ((1 - Vd/VJ)2 + 0.005)M/2

### SPICE DiodeStatic Model

Vext = vD + iD*RS

• Dinj

• IS

• N ~ 1

• IKF, VKF, N ~ 1

• Drec

• ISR

• NR ~ 2

iD*RS

Vd

DDiode

General Form

D<name> <(+) node> <(-) node> <model name> [area value]

Examples

DCLAMP 14 0 DMODD13 15 17 SWITCH 1.5

Model Form

.MODEL <model name> D [model parameters]

.model D1N4148-X D(Is=2.682n N=1.836 Rs=.5664 Ikf=44.17m Xti=3 Eg=1.11 Cjo=4p M=.3333 Vj=.5 Fc=.5 Isr=1.565n Nr=2 Bv=100 Ibv=10 0u

Tt=11.54n)

*\$

• Diode Model Parameters

• Model Parameters (see .MODEL statement)

• DescriptionUnitDefault

• ISSaturation currentamp1E-14

• NEmission coefficient1

• ISRRecombination current parameteramp0

• NREmission coefficient for ISR1

• IKFHigh-injection “knee” currentampinfinite

• BVReverse breakdown “knee” voltagevoltinfinite

• IBVReverse breakdown “knee” currentamp1E-10

• NBVReverse breakdown ideality factor1

• RSParasitic resistanceohm0

• TTTransit timesec0

• CJOZero-bias p-n capacitancefarad0

• VJp-n potentialvolt1

• Mp-n grading coefficient0.5

• FCForward-bias depletion cap. coef,0.5

• EGBandgap voltage (barrier height)eV1.11

• Diode Model Parameters

• Model Parameters (see .MODEL statement)

• DescriptionUnitDefault

• XTIIS temperature exponent3

• TIKFIKF temperature coefficient (linear)°C-10

• TBV1BV temperature coefficient (linear)°C-10

• TBV2BV temperature coefficient (quadratic)°C-20

• TRS1RS temperature coefficient (linear)°C-10

• TRS2RS temperature coefficient (quadratic)°C-20

• T_MEASUREDMeasured temperature°C

• T_ABSAbsolute temperature°C

• T_REL_GLOBALRel. to curr. Temp.°C

• T_REL_LOCALRelative to AKO model temperature°C

• For information on T_MEASURED, T_ABS, T_REL_GLOBAL, and T_REL_LOCAL, see the .MODEL statement.

• The diode is modeled as an ohmic resistance (RS/area) in series with an intrinsic diode. <(+) node> is the anode and <(-) node> is the cathode. Positive current is current flowing from the anode through the diode to the cathode. [area value] scales IS, ISR, IKF,RS, CJO, and IBV, and defaults to 1. IBV and BV are both specified as positive values.

In the following equations:

Vd= voltage across the intrinsic diode onlyVt= k·T/q (thermal voltage)k = Boltzmann’s constantq = electron chargeT = analysis temperature (°K)Tnom= nom. temp. (set with TNOM option)

### SPICE DiodeModel

• Dinj

• N~1, rd~N*Vt/iD

• rd*Cd = TT =

• Cdepl given by CJO, VJ and M

• Drec

• N~2, rd~N*Vt/iD

• rd*Cd = ?

• Cdepl =?

t

DC Current

Id = area(Ifwd - Irev)Ifwd = forward current = InrmKinj + IrecKgenInrm = normal current = IS(exp (Vd/(NVt))-1)Kinj = high-injection factorFor: IKF > 0, Kinj = (IKF/(IKF+Inrm))1/2otherwise, Kinj = 1

Irec = rec. cur. = ISR(exp (Vd/(NR·Vt))- 1)

Kgen = generation factor = ((1-Vd/VJ)2+0.005)M/2Irev = reverse current = Irevhigh + IrevlowIrevhigh = IBVexp[-(Vd+BV)/(NBV·Vt)]Irevlow = IBVLexp[-(Vd+BV)/(NBVL·Vt)}

Vext-Va=iD*Rs

low level injection

ln iD

ln(IKF)

Effect ofRs

ln[(IS*IKF) 1/2]

Effect of high level injection

ln(ISR)

Data

ln(IS)

vD=

Vext

recomb. current

VKF

### 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)

### 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.

### 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.

### 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.

### Static Model Eqns.Parameter Extraction

In the region where iD*RS >> Vd.

diD/Vd ~ 1/RSeff

dVd/diD = RSeff

### 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

1/Reff

iD

ISeff

### 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)

### 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)

### 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.

### References

Semiconductor Device Modeling with SPICE, 2nd ed., by Massobrio and Antognetti, McGraw Hill, NY, 1993.

MicroSim OnLine Manual, MicroSim Corporation, 1996.