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1D Tutorial

FET - Field Effect Transistor (1D) - How to incorporate voltage sweep steps

Author: Stefan Birner

FET - Field Effect Transistor (1D) - How to incorporate voltage sweep steps

• Here is the input file: ULM_FETs.in

1. Step 8: FET - Field Effect Transistor (1D)
   This tutorial deals with a FET including voltage sweep from 0 V to 4 V in steps of 0.2 V writing out every 1 V.
2. Please edit your keywords.in file and set the name of the file to be read in to ULM_FETs.in.
3. The structure is grown pseudomorphically on a GaN substrate.
4. This time we perform a one-dimensional simulation.
5. Just a reminder: If you need additional information about the keywords and their specifiers, you can look it up here.
6. The whole device will be calculated quantum mechanically.
7. The FET looks like this:
   
   !   1       2       3            4           5      6
! metal   n-GaN   n-GaN   Ga(0.9)In(0.1)N   GaN   metal
!   20     220     270          290         295    315      nm
!_____________________________________________________________
! ohmic contact                               ohmic contact
 
8. The structure has a constant n-type doping of 1*10¹⁸ cm^-3 from 20 nm to 269 nm.
9. Output
   - The band structure will be saved into the directory band_struc1/
- The densities will be saved into densities1/
- The strain will be saved into strain1/
- Raw data will be saved into raw_data1/
Now create these directories.
10. Voltage sweep
    
    Command to perform several calculations with increasing (decreasing) bias voltage at one specific contact.
    Useful to get I-V characteristics or to get better convergence for high bias voltage by stepwise approaching the final voltage.
    So far sweep always starts from zero voltage (probably going to be changed)
    
    Important: The output files that are generated during a voltage sweep include a index number in the file name that specifies the step number to which the file belongs.
    
     $voltage-sweep
  sweep-number            = 1
  sweep-active            = yes
  poisson-cluster-number  = 1
  step-size               = 0.20d0
  number-of-steps         = 20
  data-out-every-nth-step = 5
 $end_voltage-sweep

Example:
    cb_band001_ind000.dat: This is the first conduction band written out before the first voltage step occured.
    
    Syntax:
    sweep-active = yes / no
Flag whether voltage sweep is active or not.
    
    poisson-cluster-number = 1,2,..
Number of Poisson cluster to which bias voltage should be applied.
    
    step-size = 0.02d0  ! [V]
Step size for voltage sweep in [V], should not be larger than 0.1d0 V.
    
    number-of-steps = 10
Number of steps to be performed.
    
    data-out-every-nth-step = 1
If you don't want to write out all data specified in the output section for every step, you have to enter an integer number greater than one.
11. Output:
    That's the band structure (conduction band 1) for voltages of 0 V, 1 V, 2 V, 3 V and 4 V.
     

• Please help us to improve our tutorial. Send comments to support [at] nextnano.de.