The Fast Monte Carlo MESFET simulation

In this section we want to show how to obtain faster simulation than the previous section. First of all we simulate the MESFET device by means of the simplified MEP model. This is done by the following script

# Silicon MESFET test-1
# created on 27 feb.2005, J.M.Sellier
# modified on 05 mar.2005, J.M.Sellier
# Simplified MEP model

MATERIAL SILICON
TRANSPORT MEP ELECTRONS

FINALTIME 5.0e-12
TIMESTEP 0.001e-12

XLENGTH 0.6e-6
YLENGTH 0.2e-6

XSPATIALSTEP 90
YSPATIALSTEP 20

# Energy relaxation time
# ======================
TAUW 0.4e-12

# Definition of the doping concentration
# ======================================
DONORDENSITY    0.       0.         0.6e-6    0.2e-6    1.e23
DONORDENSITY    0.       0.15e-6    0.1e-6    0.2e-6    3.e23
DONORDENSITY    0.5e-6   0.15e-6    0.6e-6    0.2e-6    3.e23
ACCEPTORDENSITY 0.       0.         0.6e-6    0.2e-6    1.e20
# ACCEPTORDENSITY    0.       0.         0.6e-6    0.2e-6    1.e23
# ACCEPTORDENSITY    0.       0.15e-6    0.1e-6    0.2e-6    3.e23
# ACCEPTORDENSITY    0.5e-6   0.15e-6    0.6e-6    0.2e-6    3.e23

# Definition of the various contacts
# ==================================
CONTACT DOWN  0.0    0.6e-6 INSULATOR 0.0
CONTACT LEFT  0.0    0.2e-6 INSULATOR 0.0
CONTACT RIGHT 0.0    0.2e-6 INSULATOR 0.0
CONTACT UP    0.1e-6 0.2e-6 INSULATOR 0.0
CONTACT UP    0.4e-6 0.5e-6 INSULATOR 0.0
CONTACT UP    0.0    0.1e-6 OHMIC     0.0 3.e23 1.e20
CONTACT UP    0.2e-6 0.4e-6 SCHOTTKY -0.8
CONTACT UP    0.5e-6 0.6e-6 OHMIC     1.0 3.e23 1.e20

NOQUANTUMEFFECTS
MAXIMINI
# SAVEEACHSTEP

LATTICETEMPERATURE 300.

STATISTICALWEIGHT 100
MEDIA 500

OUTPUTFORMAT GNUPLOT

# end of MESFET test-1

Then we copy the density, energy and potential files with the following names

 density_start.xyz
 energy_start.xyz
 potential_start.xyz

and run the following script

# Silicon MESFET test-1
# created on 27 feb.2005, J.M.Sellier
# modified on 05 mar.2005, J.M.Sellier
# Fast Monte Carlo method

MATERIAL SILICON
TRANSPORT MC ELECTRONS

FINALTIME 1.e-12
TIMESTEP 0.001e-12

XLENGTH 0.6e-6
YLENGTH 0.2e-6

XSPATIALSTEP 90
YSPATIALSTEP 20

# Energy relaxation time
# ======================
TAUW 0.4e-12

# Definition of the doping concentration
# ======================================
DONORDENSITY    0.       0.         0.6e-6    0.2e-6    1.e23
DONORDENSITY    0.       0.15e-6    0.1e-6    0.2e-6    3.e23
DONORDENSITY    0.5e-6   0.15e-6    0.6e-6    0.2e-6    3.e23
ACCEPTORDENSITY 0.       0.         0.6e-6    0.2e-6    1.e20
# ACCEPTORDENSITY    0.       0.         0.6e-6    0.2e-6    1.e23
# ACCEPTORDENSITY    0.       0.15e-6    0.1e-6    0.2e-6    3.e23
# ACCEPTORDENSITY    0.5e-6   0.15e-6    0.6e-6    0.2e-6    3.e23

# Definition of the various contacts
# ==================================
CONTACT DOWN  0.0    0.6e-6 INSULATOR 0.0
CONTACT LEFT  0.0    0.2e-6 INSULATOR 0.0
CONTACT RIGHT 0.0    0.2e-6 INSULATOR 0.0
CONTACT UP    0.1e-6 0.2e-6 INSULATOR 0.0
CONTACT UP    0.4e-6 0.5e-6 INSULATOR 0.0
CONTACT UP    0.0    0.1e-6 OHMIC     0.0 3.e23 1.e20
CONTACT UP    0.2e-6 0.4e-6 SCHOTTKY -0.8
CONTACT UP    0.5e-6 0.6e-6 OHMIC     1.0 3.e23 1.e20

NOQUANTUMEFFECTS
MAXIMINI
# SAVEEACHSTEP

# Load Electron Initial Data
LEID

LATTICETEMPERATURE 300.

STATISTICALWEIGHT 100
MEDIA 500

OUTPUTFORMAT GNUPLOT

# end of MESFET test-1

As the reader can note from the following script, we only need $1$ picosecond for the Monte Carlo method. This is done because we load the initial conditions from the previous MEP simulation. This is a very fast way to obtain fast Monte Carlo simulations. We report, in the following some interesting results.

Figure: MESFET MEP Energy Profile computed by GNU Archimedes.

Figure: MESFET Fast Monte Carlo Energy Profile computed by GNU Archimedes.

Figure: MESFET MEP potential computed by GNU Archimedes.

Figure: MESFET Fast Monte Carlo Potential computed by GNU Archimedes.