QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: IzzatiShahirah on November 1, 2017, 10:20

Title: Stress at gate of MOSFET
Post by: IzzatiShahirah on November 1, 2017, 10:20

Hi all,
How to put stress on the gate of MOSFET.
I already tried it. Only values in matrices were shown . It is 3x3 matrices.
What does it mean? 

Title: Re: Stress at gate of MOSFET
Post by: Daniele Stradi on November 1, 2017, 10:32

Could you please define better what you mean by "put stress on the gate"? It would be also of great help if you could attach a script with your calculation.

Thanks!
Daniele

Title: Re: Stress at gate of MOSFET
Post by: IzzatiShahirah on November 2, 2017, 15:55

The coding is something like this.

# Set up configuration
bulk_configuration = BulkConfiguration(
    bravais_lattice=FaceCenteredCubic(5.4*Angstrom),
    elements=[Gallium, Arsenic],
    cartesian_coordinates=[[ 0.      ,  0.      ,  0.      ],
                         [ 1.413425,  1.413425,  1.413425]]*Angstrom
    )

calculator = LCAOCalculator(
    numerical_accuracy_parameters=NumericalAccuracyParameters(
    k_point_sampling=(4, 4, 4))
    )

bulk_configuration.setCalculator(calculator)

#calculate the stress
stress = Stress(bulk_configuration)
nlprint(stress)

After simulation, 3x3 matrices appeared. There was no something like "Stress = 4.12111" .

Title: Re: Stress at gate of MOSFET
Post by: Daniele Stradi on November 2, 2017, 17:17

The reason for the appearance of a 3x3 matrix is that the stress is actually a tensorial quantity, see e.g.:
https://en.wikipedia.org/wiki/Cauchy_stress_tensor

What you probably want is the hydrostatic stress:
https://en.wikipedia.org/wiki/Hydrostatic_stress

If you want the hydrostatic component of the stress, you can calculate it from the trace of the 3x3 matrix.

Regards,
Daniele

Title: Re: Stress at gate of MOSFET
Post by: IzzatiShahirah on November 7, 2017, 17:45

Thank you for the information, Daniele  :D