I was using "Thermodynamic Transport" Model as given in Sentaurus Device Tutorial as "Thermo_des.cmd". It was showing different lattice temperatures in "@node@_des.tdr" file. Temperature was 707 to 745 K. Is this approach correct? If no then how to turn ON self heating?
But if Yes, then how to turn OFF self heating? I have deleted the "Temperature" word from the line "Coupled{ Poisson Electron Hole Temperature }" in three places of "Solve" section. 1) "*- Build-up of initial solution:", 2) "*- Bias gate to target bias", and 3) "*- drain voltage sweep". Then "@node@_des.tdr" file is NOT showing different lattice temperatures. It is 300 K. But the problem is drain current has decreased.
We know that higher temperature changes the temperature dependent material properties like band-gap and mobility, leading to the degradation of device performance. The reduction in mobility leads to a reduction in output current as the operation voltage is increased.
But in my case self heating off showing lower current and self heating on showing higher current.
I was simulating an NMOSFET of conventional structure taking parameters from ITRS 2013.
Please inform how to do self heating ON and OFF.
The word "Temperature" in the coupled section works as thermodynamic transport. But as the word is deleted, the device is calculated using drift-diffusion transport. Because of this, transport-related parameters are different between drift-diffusion and thermodynamic transports as shown in the Sentaurus Device manual. So, just deleting temperature in the coupled section can't show the self-heating effect.
If you want to off the self-heating effects using thermodynamic transport, then you can fix temperature by adding the comment "Temperature = ~ K" in the global physics section.
I hope this can help your problem
Best regards,
Jun-Sik Yoon
Thank you very much Jun-Sik Yoon for your answer. Please guide a little bit more. When I added "Temperature = ~ K", it is showing syntax error, offending input: ~ K , Then I changed "Temperature = 300 K", it is showing Unrecognized keyword 'K' , Then I changed to "Temperature = 300" in the global physics section, this time simulation completed successfully, but the result drain current is same as it was when the line was not mentioned. There are different temperature in different lattice position. I want drain current should differ when self heating effect or SHE is ON and OFF. But here is no difference.
Actually, when you just add "thermodynamic" without including any temperature-dependent mobility models, thermodynamic tutorial has higher drain current than drift-diffusion because of band-gap narrowing and carrier-generation.
Well... there is an other method to force the limit called "lT_Range" but I am not sure whether this works or not.
Thank you Dr. Jun-Sik Yoon. I am sending the code of SDEVICE as it is. Please check if this works for SHE ON condition. If not then please provide the full code. Please also inform how to OFF the SHE (full code).
-------------------------------------------------
* Thermo
File{
Grid = "@tdr@"
Plot = "@tdrdat@"
Parameter = "@parameter@"
Current = "@plot@"
Output = "@log@"
}
Electrode{
{ Name="source" Voltage=0.0 }
{ Name="drain" Voltage=0.0 }
{ Name="gate" Voltage=0.0 }
{ Name="substrate" Voltage=0.0 }
}
Thermode{ { Name="substrate" Temperature=300 SurfaceResistance=5e-4 } }
Physics{
Thermodynamic
eQCvanDort
EffectiveIntrinsicDensity( OldSlotboom )
Mobility(
DopingDep
eHighFieldsaturation( GradQuasiFermi )
hHighFieldsaturation( GradQuasiFermi )
Enormal
)
Recombination(
SRH( DopingDep TempDependence )
)
}
Plot{
*--Density and Currents, etc
eDensity hDensity
TotalCurrent/Vector eCurrent/Vector hCurrent/Vector
eMobility hMobility
eVelocity hVelocity
eQuasiFermi hQuasiFermi
*--Heat quantities
Temperature * eTemperature hTemperature
TotalHeat eJouleHeat hJouleHeat
*--Fields and charges
ElectricField/Vector Potential SpaceCharge
*--Doping Profiles
Doping DonorConcentration AcceptorConcentration
*--Generation/Recombination
SRH Band2Band * Auger
AvalancheGeneration eAvalancheGeneration hAvalancheGeneration
*--Driving forces
eGradQuasiFermi/Vector hGradQuasiFermi/Vector
eEparallel hEparallel eENormal hENormal
*--Band structure/Composition
BandGap
BandGapNarrowing
Affinity
ConductionBand ValenceBand
eQuantumPotential
}
Math {
Extrapolate
Iterations=20
Notdamped =100
RelErrControl
ErRef(Electron)=1.e10
ErRef(Hole)=1.e10
}
Solve {
*- Build-up of initial solution:
NewCurrentPrefix="init"
Coupled(Iterations=100){ Poisson }
Coupled{ Poisson Electron Hole Temperature }
*- Bias gate to target bias
Quasistationary(
InitialStep=0.01 Increment=1.35
MinStep=1e-5 MaxStep=0.2
Goal{ Name="gate" Voltage= 0.8 }
){ Coupled{ Poisson Electron Hole Temperature } }
*- drain voltage sweep
NewCurrentPrefix=""
Quasistationary(
InitialStep=1e-3 Increment=1.35
MinStep=1e-5 MaxStep=1.1
Goal{ Name="drain" Voltage= 0.8 }
){ Coupled{ Poisson Electron Hole Temperature }
CurrentPlot(Time=(Range=(0 1) Intervals=20))
}
}
Debasis Mukherjee Hello were you able to get drain current degradation after turning on the self heating. I really want to know as I want to study self heating in AlGaN HEMT
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