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qcl:input_file [2019/04/08 15:09] thomas.grange [Gain (optional)] |
qcl:input_file [2020/05/21 20:50] thomas.grange [Simulation parameters] |
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</code> | </code> | ||
- | Note that ''<Overwrite>'' has higher priority than ''<OverwriteMaterial>''. | + | Note that ''<Overwrite>'' has higher priority than ''<Overwrite_Material_Database>'' (see below). |
=== Conduction or valence band offsets === | === Conduction or valence band offsets === | ||
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Note that alloy scattering is only considered for the material specified by <Material_for_scattering_parameters>. | Note that alloy scattering is only considered for the material specified by <Material_for_scattering_parameters>. | ||
+ | By default the following alloy squared matrix element for a zinc-blende ternary $A_{x}B_{1-x}C$ is considered: | ||
+ | $$ | ||
+ | \vert \langle \alpha,k_0 \vert H_{\text{alloy}} \vert \beta,k_0+k \rangle\vert^2 = \int dz \frac{x(1-x) a^3 \Delta E_c}{4} \vert \phi_{\alpha}(z) \phi_{\beta}(z) \vert^2 | ||
+ | $$ | ||
+ | where $\Delta E_c$ is the conduction band offset between the binaries $AC$ and $BC$. | ||
+ | |||
+ | This squared matrix element can be tuned with respect to the above formula by using the following command (tuning the squared matrix element is equivalent of tuning the scattering rate): | ||
<code> | <code> | ||
+ | <Alloy_scattering> yes </Alloy_scattering> | ||
+ | <Tune_Alloy_scattering>0.5</Tune_Alloy_scattering> | ||
</Scattering> | </Scattering> | ||
</code> | </code> | ||
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<code> | <code> | ||
<Tune_Elect_Elect_Scattering_Strength>yes</Tune_Elect_Elect_Scattering_Strength> | <Tune_Elect_Elect_Scattering_Strength>yes</Tune_Elect_Elect_Scattering_Strength> | ||
- | <Elect_Elect_Scattering_Strength>1.5</Elect_Elect_Scattering_Strength> ( a value of 1.0 gives the normal calculation) | + | <Elect_Elect_Scattering_Strength>1.5</Elect_Elect_Scattering_Strength> |
</code> | </code> | ||
+ | A value of 1.0 gives the normal calculation. | ||
==== Poisson equation ==== | ==== Poisson equation ==== | ||
The electrostatic mean-field interactions (electron-electron and electron-impurities interactions) can be switched on/off by using ''yes'' or ''no'' in the ''<Poisson>'' command. | The electrostatic mean-field interactions (electron-electron and electron-impurities interactions) can be switched on/off by using ''yes'' or ''no'' in the ''<Poisson>'' command. | ||
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* ''N'' ==> coherent transport between N+1 periods | * ''N'' ==> coherent transport between N+1 periods | ||
In almost all existing QCL designs, 1 is enough. The user should not change this value. (Larger number are needed for superlattices. | In almost all existing QCL designs, 1 is enough. The user should not change this value. (Larger number are needed for superlattices. | ||
+ | |||
+ | The coherence length for which self-energies are considered can be further limit by using the following command: | ||
+ | <code> | ||
+ | <Simulation_Parameter> | ||
+ | <Coherence_length_in_nm>50.0</Coherence_length_in_nm> | ||
+ | ... | ||
+ | </Simulation_Parameter> | ||
+ | </code> | ||
+ | Such limitation will speed up the calculation of the self-energies. On the other hand, this can reduce the accuracy of the scattering processes if this length is below the actual coherence length in the simulated device. | ||