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  Global parameters

 

 

 
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Global parameters

Global parameters are general parameters which are valid all over the device.
See also $global-parameters under Database section.

Lattice Temperature


!----------------------------------------------------------!
$global-parameters                               optional  !
                                                           !
 lattice-temperature                 double      required  !

                                                           !
 temperature-sweep-active            character   optional  !
(optional, only needed for temperature sweep)
 temperature-sweep-step-size         double      optional  !
(optional, only needed for temperature sweep)
 temperature-sweep-number-of-steps   integer     optional  !
(optional, only needed for temperature sweep)
 data-out-every-nth-step             integer     optional  !
(optional, only needed for temperature sweep)
                                                          
!
$end_global-parameters                           optional  !

!----------------------------------------------------------!

 

Syntax

!----------------------------------------------------------!
$global-parameters
                                         !
                                                           !
 lattice-temperature               = 300d0                 ! [K]
                                                           !
 temperature-sweep-active          = yes                   ! yes/no

 temperature-sweep-step-size       = -10d0                 ! [K], i.e. in this case -10 K
 temperature-sweep-number-of-steps = 20                    !  number of temperature sweep steps
 data-out-every-nth-step           = 10                    ! (optional, default = 1)
                                                          
!
$end_global-parameters                                     !
!----------------------------------------------------------!

 

The lattice temperature is given in Kelvin.

Note: $global-parameters is optional. If it is not present, the default value for the temperature is taken from $global-parameters of the database file. Currently, the default temperature is set to 300 K.

 

 

Attention

The band gaps (namely the conduction band edge only) are adjusted when the temperature changes.
This feature can be switched off. See $numeric-control:
varshni-parameters-on.

In addition, the lattice constants depend on temerature. This can be switched off as well.
See $numeric-control:
lattice-constants-temp-coeff-on.

 

 

Temperature sweep

It is possible to sweep over the temperature, i.e. to vary the temperature stepwise. This is similar to electric field sweeps ($electric-field), magnetic field sweeps ($magnetic-field), voltage sweeps ($voltage-sweep) and doping concentration sweeps ($doping-function).
The output is labeled with ..._ind000.dat, ..._ind001.dat, ..._ind002.dat, ... where the index refers to the number of the temperature sweep step.

 lattice-temperature               = 300d0     ! default is 300d0  ! [K]
 temperature-sweep-active          = yes       !
default is no     ! yes/no
 temperature-sweep-step-size       = -10d0     ! default is 0d0    ! [K], i.e. in this case -10 K
 temperature-sweep-number-of-steps = 20        ! default is 0      !  number of temperature sweep steps
 data-out-every-nth-step           = 10        ! default is 1      !

In the above shown example, the temperature is varied starting from 300 K, and then reducing the temperature 20 times in steps of "-10 K", ending at 100 K. Obviously, increasing the temperature is also possible.
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.
If you specify 1, then output files will be generated for each temperature sweep. This is useful if you want to fill out all unused space on your hard disk.

 

Restrictions:

  •  flow-scheme = 13  ,
     flow-scheme = 130 ,
     flow-scheme = 14  and
     flow-scheme = 140 have some special functionality so far.

    130/140: same as 13/14 but including self-consistent Poisson-Schrödinger.

     flow-scheme = 13: vary temperature as T
         lattice-temperature               = 5d0   ! 5 Kelvin
         temperature-sweep-active          = yes   !
         temperature-sweep-step-size       = 5d0   !
    increase by 5 K
         temperature-sweep-number-of-steps = 250   !
         data-out-every-nth-step           = 50    !

     flow-scheme = 14
    : vary temperature as 1000/T
         lattice-temperature               = 1250d0 ! 1250 Kelvin
         temperature-sweep-active          = yes    !
         temperature-sweep-step-size       = -5d0   !
    decrease by 5 K
         temperature-sweep-number-of-steps = 250    !
         data-out-every-nth-step           = 50     !

    See tutorial Electron concentration in doped semiconductors (Si, Ge, GaAs) for details.

 

 

Question

Can I change the lattice-temperature to 0 Kelvin in the input file?

Answer

-> $program-restrictions