View source for T-Gate, Electric Field (2D) - full deck

NOTE: The files '''"GaN Models Simple (2D)"''' and '''"TgateDimensions"''' must be saved and included in the same directory as this "T-Gate" file, or have paths pointing to these files, in order to run this T-Gate script. These two previously mentioned files are sourced within this T-Gate script to define material characteristics and to define the gate size in the grid. Links to these files are provided.


 
 DevicePackage

 pdbSetDouble Math iterLimit 800
 pdbSetDouble Math rhsLimit 1.0e-15
 pdbSetDouble Math updateLimit 1.0e-6
 math device dim=2 col umf none scale

This command sources the '''"GaN Models Simple"''' file. It is now set such that the "GaN Models Simple" file is in the same directory as this T-Gate script.

 source [[GaN Models Simple (2D) - full deck]]
 #source GaN_ETemp

 mater add name=Metal
 mater add name=OxPhase
 mater add name=Nitride

 #Set up solution for displacement 
 solution name = displacement add solve dim continuous negative
 solution name = Temp add solve 

 math diffuse dim=2 umf none col !scale 

 pdbSetBoolean GaN displacement Negative 1 
 pdbSetBoolean ReflectLeft displacement Negative 1 
 pdbSetDouble GaN displacement Abs.Error 1.0e-8 
 pdbSetDouble ReflectLeft displacement Abs.Error 1.0e-8 

 pdbSetBoolean AlGaN displacement Negative 1 
 pdbSetBoolean ReflectLeft displacement Negative 1 
 pdbSetDouble AlGaN displacement Abs.Error 1.0e-8 
 pdbSetDouble ReflectLeft displacement Abs.Error 1.0e-8

 pdbSetBoolean Nitride displacement Negative 1 
 pdbSetBoolean ReflectLeft displacement Negative 1 
 pdbSetDouble Nitride displacement Abs.Error 1.0e-8 
 pdbSetDouble ReflectLeft displacement Abs.Error 1.0e-8

 pdbSetBoolean OxPhase displacement Negative 1 
 pdbSetBoolean ReflectLeft displacement Negative 1 
 pdbSetDouble OxPhase displacement Abs.Error 1.0e-8 
 pdbSetDouble ReflectLeft displacement Abs.Error 1.0e-8

 pdbSetBoolean ReflectRight displacement Negative 1 
 pdbSetDouble ReflectRight displacement Abs.Error 1.0e-8

 #Fix base 
 pdbSetBoolean ReflectBottom displacement Fixed 1 
 pdbSetString ReflectBottom displacement Equation "displacement" 
 
 #Fix sides 
 pdbSetBoolean ReflectLeft displacement Fixed 1 
 pdbSetString ReflectLeft displacement Equation "displacement" 

 pdbSetBoolean ReflectRight displacement Fixed 1 
 pdbSetString ReflectRight displacement Equation "displacement" 

 pdbSetString GaN displacement Equation "elastic(displacement)" 
 pdbSetString AlGaN displacement Equation "elastic(displacement)-BodyStrain(0.004)+IPZ(DevPsi)" 
 #pdbSetString AlGaN displacement Equation "elastic(displacement)+BodyStrain(0.004)
 pdbSetString OxPhase displacement Equation "elastic(displacement)" 
 pdbSetString Nitride displacement Equation "elastic(displacement)+BodyStrain(0.00005)" 

This command sources the '''"TgateDimensions"''' file. It is now set such that the "TgateDimensions" file is in the same directory as this T-Gate script. The AlGaN is now set to a 25nm thickness and gate length at the bottom is 0.3um. 
  
 source [[T-Gate Dimensions file (2D) - full deck]]

These lines create the device structure and define the grid sizing:

    line x loc=-0.2 spac=0.01 tag=Gwt
    line x loc=-0.1 spac=0.01 tag=Gwb
    line x loc=-0.005 spac=0.001 tag=Ox
    line x loc=0.0 spac=0.001 tag=AlGaNTop
    line x loc=$Althick spac=0.005 tag=AlGaNBottom
    line x loc=1.0 spac=0.1 tag=BBottom

    line y loc=-1.0 spac=0.05 tag=Left
    line y loc=$Gtl spac=0.02 tag=sidewL
    line y loc=$Gbl spac=0.02 tag=sidenL
    line y loc=$Gbr spac=0.02 tag=sidenR
    line y loc=$Gtr spac=0.02 tag=sidewR
    line y loc=1.0 spac=0.05 tag=Right

    #Bulk
    region GaN xlo=AlGaNBottom xhi=BBottom ylo=Left yhi=Right

    #AlGaN under gate
    region AlGaN xlo=AlGaNTop xhi=AlGaNBottom ylo=Left yhi=Right
    
   #Metal alloy for T-gate
    region Metal xlo=Gwt xhi=Gwb ylo=sidewL yhi=sidewR
    region Metal xlo=Gwb xhi=Ox ylo=sidenL yhi=sidenR

   #Nitride cap layer 
    region Nitride xlo=Gwt xhi=Gwb ylo=Left yhi=sidewL
    region Nitride xlo=Gwt xhi=Gwb ylo=sidewR yhi=Right
    region Nitride xlo=Gwb xhi=Ox ylo=Left yhi=sidenL
    region Nitride xlo=Gwb xhi=Ox ylo=sidenR yhi=Right

    #Created Oxide layer
    region OxPhase xlo=Ox xhi=AlGaNTop ylo=Left yhi=Right

    init 

    #Contacts
    contact name=G Metal xlo=-0.195 xhi=-0.002 ylo=[expr {$Gtl-$buf}] yhi=[expr {$Gtr+$buf}] add depth=1.0 width=1.0
    contact name=B GaN xlo=0.9 xhi=1.1 ylo=-1.0 yhi=1.0 add depth=1.0 width=1.0
    contact name=S AlGaN ylo=-1.0 yhi=-0.9 xlo=-0.7 xhi=0.0005 add depth=1.0 width=1.0
    contact name=D AlGaN ylo=0.9 yhi=1.0 xlo=-0.7 xhi=0.0005 add depth=1.0 width=1.0

    contact name=G current=(Hole_AlGaN-Elec_AlGaN) voltage supply=0.0
    contact name=B current=(Hole_GaN-Elec_GaN) voltage supply=0.0
    contact name=D current=(Hole_GaN-Elec_GaN) voltage supply=0.0
    contact name=S current=(Hole_GaN-Elec_GaN) voltage supply=0.0
      
   #doping definition-will use method from pfmos_qf deck for simplicity
    #GaN Doping-from Dessis file from Heller-acceptor-p-type
    sel z=-6.5e16*Mater(GaN) name=GaN_Doping
    
    #AlGaN Doping-from Dessis file from Heller-he puts equivalent donor and acceptor doping in region to signify traps
    sel z=1e12 name=AlGaN_Doping
    #sel z=1e12*Mater(OxPhase) name=OxPhase_Doping
    #sel z=1e20*Mater(Metal)*(x>=-0.2)*(x<=-0.002)*(y>$Gtl)*(y<$Gtr) name=Metal_Doping
    sel z=1e20*(x>=-0.2)*(x<=-0.002)*(y>$Gtl)*(y<$Gtr) name=Metal_Doping
   
    #Source and Drain contact doping-from contact to 2DEG like Heller-just to make contacts ohmic
    sel z=(1e19*(y>0.75)+(y<=0.75)*1.0e19*exp(-(y-0.75)*(y-0.75)/(0.75*0.02*0.02)))*(exp(-(x*x)/(2.0*0.03*0.03)))*(x>=0.0) name=Drain_Doping
    sel z=(1e19*(y<-0.75)+(y>=-0.75)*1.0e19*exp(-(y+0.75)*(y+0.75)/(0.75*0.02*0.02)))*(exp(-(x*x)/(2.0*0.03*0.03)))*(x>=0.0) name=Source_Doping

     #Total doping
    #sel z=GaN_Doping+AlGaN_Doping+Drain_Doping+Source_Doping+Metal_Doping+OxPhase_Doping name=Doping
    sel z=GaN_Doping+AlGaN_Doping+Drain_Doping+Source_Doping+Metal_Doping name=Doping
    sel z=0.26 name=AlN_Ratio

These procedures set up the options to plot the entire device, "Plot", or just the gate area, "Plotsmall":

 proc Plot {} {
 plot.2d bound
 plot.2d contact=G !cle
 plot.2d contact=B !cle
 plot.2d contact=S !cle
 plot.2d contact=D !cle
 plot.2d contact=F1 !cle
 plot.2d contact=F2 !cle
 }
 proc Plotsmall {} {
 plot.2d bound min = {-2e-5  -4e-5}  max = {1.5e-5  4e-5} 
 plot.2d contact=G !cle
 }
 proc Plotasy {} {
 plot.2d bound min = {-2e-5  -6.5e-5}  max = {1.5e-5  1.5e-5} 
 plot.2d contact=G !cle
 }

  Initialize

 device init

The procedures '''OFFStateField''' and '''ONStateField''' set up the respective conditions for producing a 1D plot of the Electric field in the device ,from left to right, just under the surface of the AlGaN. The peaks produced in the plot correspond to the gate edges, where the field is highest. The procedure is now set to "OFFStateField":

 proc OFFStateField {} {
 #set Vgs -1.0
 set Vgs -5.0
 set Vdd 0.0
 set Vss 0.0
 }
 OFFStateField

 proc ONStateField {} {
 set Vgs -1.0
 #set Vgs -5.0
 set Vdd 0.0
 set Vss 0.0
 }
 #ONStateField

 proc Vds0Field {} {
 #set Vgs -1.0
 set Vgs -5.0
 set Vdd 0.0
 set Vss 0.0
 }
 #Vds0Field

 for {set Vdd 0.00} {$Vdd<5.4} {set Vdd [expr $Vdd+1]} {

 contact name=D supply=$Vdd
 contact name=G supply=$Vgs
 contact name=S supply=$Vss

This expression determines the electric field:

 sel z=(sqrt(dot(DevPsi,DevPsi)+1.0)) name=Efield
 sel z=Efield
 plot.1d x.v=0.001

 device

 }