surface-potential-based gan hemt compact …...• physics-based model for gan hemts presented •...

ASM GaN HEMT: Advanced SPICE Model

for GaN HEMTs

Sourabh Khandelwal, T. A. Fjeldly, B. Iniguez, Y. S. Chauhan, S. Ghosh, A. Dasgupta

MOS-AK 2014

Sourabh Khandelwal MOS-AK 2014 1

Outline• ASM-HEMT Model Background • Model Description

• Overview• 2-DEG Charge Density & Surface-Potential Model• Drain-Current, Gate-Current Model • Charge and Capacitance Model• Flicker Noise and Thermal Noise Models

• Model Results• Model Parameter Extraction• DC I-V Results: Drain and Gate-Current On industry data• S-parameter validation for multiple DC bias points• Power Sweep Harmonic Balance Simulation Results

• Model Quality Testing• Gummel DC and AC Symmetry• Physical behavior of capacitances

• Conclusions Sourabh Khandelwal MOS-AK 2014 2

ASM-HEMT Model Background• Started as PhD Thesis Work at UNIK/NTNU, Norway

• Sourabh Khandelwal and Prof. Tor A. Fjeldly• “Compact Modeling Solutions for Advanced Semiconductor

Devices” PhD Thesis NTNU 2013:248• EU Project COMON

• In Collaboration with• Prof. B. Iniguez, URV Spain• Prof. Yogesh S. Chauhan, IIT Kanpur

• Model passed into the Phase-II for standardization at the Compact Model Coalition (CMC)

• Two sponsor companies


ASM-HEMT Model Overview• Schrӧdiger’s & Poisson’s solution for core SP calculation• Drain current model includes all the important real

device effects• Velocity Saturation, DIBL, Mobility Degradation, Temperature

effects, Non-linear access region resistances, SS degradation…• Gate Current Model

• Frenkel-Poole Mechanism• Self-Heating Effect Model• Model for Trapping effects• Flicker Noise Model• Thermal Noise Model


ASM-HEMT Model Overview


Analytical Solution of Schrӧdiger’s & Poisson’s

SP-Based Id Ig & ChargeModelReal Device effects included

Noise Model, Trapping EffectsModel, Self-Heating

2-DEG ChargeFermi-level (Ef),Surface-potential (SP)

Accurate I-V and C-VPhysical parametersDIBL, Rs, VS, ...

DC, AC, TransientHarmonic Simulations,Noise


Surface-Potential Modeling

• Basic device equations are transcendental in nature

• We divide variation of Ef with Vg into regions to develop fully analytical expression

• Regional models are combined in one analytical expression

• No fitting parameters introduced

Surface-Potential Model


/ , / /s d f s d s dE Vψ = +S. Khandelwal et al. IEEE TED vol. 59, no. 10, 2012


Drain-Current Model

• Core Drain Current Model

• Velocity-Field relation and mobility-degradation

Access Region Resistance

• Non-linear model for access region resistances• Accounts for velocity saturation in access region


S DG

AlGaN

GaN

G

DS

Intrinsic

Rd = f(Vg, Vd)Rs = f(Vg, Vd)

Self-Heating Model


Temperature

Rth CthPd

Self-Heating effect model in ASM-HEMT

TemperatureDependent

Parameters, calculations in

the model


Intrinsic Charge Modeling

• Surface-Potential Based Charge Expressions• Consistent I-V and C-V calculations

• Ward-Dutton Partioning for source and drain charges

( )

( )

( )

0

0

0

, .

, .

1 , .

L

g s g x

L

d s g x

L

s s g x

Q Wqn V V dx

xQ Wqn V V dxL

xQ Wqn V V dxL

=

=

= −

∫

∫

∫

Charge Conservation


• Analytical Expressions for all terminal charges

• All Device Capacitances:

𝐶𝐶𝑖𝑖𝑖𝑖 =𝜕𝜕𝜕𝜕𝜕𝜕𝜕𝜕𝜕𝜕𝜕𝜕

• Correct physical behavior of capacitances

• Parasitic Capacitances added to intrinsic capacitance model


Gate Current Model• Reverse Gate Leakage Mechanism

• Frenkel-Poole Model

• Forward Gate Current


Surface-Potential-Based

Flicker Noise Model

Sourabh Khandelwal MOS-AK 2014 15L= 0.7 um GaN Device

L=0.35 um GaAs device

Thermal Noise Model


Model Inputs and Parameters


• Physical Constants– D, q, ...

• Simulation Conditions– Vg, Vd, T...

• Device Dimensions– L, W, d, ..

• Physically-Linked Model Parameters

Parameter Physical MeaningU0 Low field MobilityUA Mobility degradation parameterUB Mobility degradation parameterVOFF Cut-off Voltage of DeviceVSAT Saturation VelocityRTH Thermal ResistanceDIBL DIBL effect parameterVOFFT Temperature dependence of VoffUTE Mobility dependence of mu0RS Source Side Resistance

RD Drain Side Resistance... …

Model Parameter Extraction


Set L, W, NF, TbarDevice Dimensions

Obtain VOFF, NF, CDSCD, ETA from log-IDVG, LINEAR

And Saturation

Obtain U0, UA, UB and RDS from IDVG-LIN

Obtain VSAT, Improve ETAFrom LINEAR IDVG

Obtain LAMBDA, Improve VSAT, ETA from IDVD

Temperature Parameters

Capacitance Modeling

Noise Modeling

Extraction flow similar to standard physics-based models Parameters linked to physical effects

GaN Model Results DC I-V


Calibration for Channel Lengths L = 1 um and L = 0.7 um

DC Fitting Results with Industry Data


IDVG for various VDS

VD1 VD2 VD3

VD4 VD5

Sub-threshold ID for various VD

VD1 VD2

VD3

VD4VD5

GMVG for various VD

VD1

VD2

VD3

VD4VD5

GM’VG for various VD

VD1 VD2 VD3

VD4 VD5

GM’’VG for various VD

VD1VD2 VD3

VD4 VD5

Smooth, Continuous and Accurate ID and its derivatives

S-Parameter Data Fitting Results

S-parameter Fitting Vs Frequency@ Bias1

|S11|

|S12|

|S22|

|S21|


Ph-S11

Ph-S12

Ph-S22

Ph-S21


|H21|

K

Max Gain


|S11||S22|

|S12|

|S21|


Ph-S11Ph-S22

Ph-S12 Ph-S21


H21

K

Max-Gain

RF Power Sweep GaN Device Tuned for maximum power

Harmonic Balance Results


Accurate Pout and PIM3 prediction by model at various bias points

S. Khandelwal et al., IEEE MTT, vol. 61, no. 9, 2013

Model Quality: GummelSymmetry Test


Symmetric, Continuous and Smooth Model Behavior

Model Quality: Capacitances


Model Passes Gummel AC Symmetry Tests

GS GDcg

GS GD

C CC C

δ −=

+𝛿𝛿𝑐𝑐𝑐𝑐𝑐𝑐 =

𝐶𝐶𝑆𝑆𝑆𝑆 − 𝐶𝐶𝐷𝐷𝐷𝐷𝐶𝐶𝑆𝑆𝑆𝑆 + 𝐶𝐶𝐷𝐷𝐷𝐷

Model Quality: Capacitances


Correct Physical behavior of capacitances

Conclusions• Physics-based Model for GaN HEMTs presented

• Schrodinger’s and Poisson’s based surface-potential analytical calculation

• Drain and Gate Current• Charges and Capacitances Model • Real Device effects (CLM, DIBL, Self-Heating etc.) included• Flicker Noise and Thermal Noise models

• Excellent Agreement with industry quality measured data

• DC, S-parameters, Power Sweep• Model passes important quality test

• Gummel Symmetry, AC Symmetry, Harmonic Balance etc.


References1. Sourabh Khandelwal , Chandan Yadav, Shantanu Agnihotri, Yogesh Singh Chauhan, Arnaud

Curutchet, Thomas Zimmer, Jean-Claude Dejaeger, Nicolas Defrance, and Tor A. Fjeldly, "A robust surface-potential-based compact model for GaN HEMT IC design", IEEE Trans. Electron Devices, vol. 60, no. 10, pp. 3216-3222, 2013

2. Sourabh Khandelwal , and Tor A. Fjeldly, "Analysis of Drain-Current Nonlinearity Using Surface-Potential-Based Model in GaAs pHEMTs", IEEE Trans. Microwave Theory and Tech., vol. 61, no. 9, pp. 3265-3270, Sep. 2013.

3. Sourabh Khandelwal , Yogesh Singh Chauhan and Tor A. Fjeldly, "Analytical modeling of surface-potential and intrinsic charges in AlGaN/GaN HEMT devices", IEEE Trans. Electron. Devices vol. 59, no. 10 pp. 2856-2860, Oct. 2012.

4. Sourabh Khandelwal , Nitin Goyal, and Tor A. Fjeldly, "A Physics based analytical model for 2-DEG charge density in AlGaN/GaN HEMT devices", IEEE Trans. Electron Devices vol. 58, no. 10 pp. 3622-3625, Oct. 2011.

5. S. Khandelwal and Tor A. Fjeldly, "A surface-potential-based compact model for study of non-linearities in AlGaAs/GaAs HEMTs", Proc. Compound Semiconductor IC Symp., pp. 1-4, Oct. 2012, San Diego, USA.

6. A. Dasgupta, S. Khandelwal, and Y. S. Chauhan, “Compact Modeling of flicker noise in HEMTs” JEDS 2014.

7. S. Ghosh, A. Dasgupta, S. Khandelwal, et al. “Surface-potential-based compact modeling of gate current in AlGaN/GaN HEMTs” IEEE TED 2014


Thank You for Attention !


surface-potential-based gan hemt compact …...• physics-based model for gan hemts presented •...

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