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For each simulation run, a new output folder is created in the simulation output folder. The created folder has the name of the input file. In addition date-time is added to the folder name if the option is selected in Options→Expert settings of nextnanomat (this option is recommended in order to avoid overwritten existing output data). The created output folder contains:
The folder Input/
contains all information that is input to the simulation such as material parameters.
AlloyContent.dat
Al(x)Ga(1-x)As
BandEdge_conduction.dat
BandEdges.dat
BandGap.dat
DeformationPotential_ConductionBand.dat
EffectiveMass.dat
ElasticConstants.dat
EpsOptic.dat
EpsStatic.dat
LatticeConstants.dat
MaterialDensity.dat
PhononEnergy_LO.dat
PiezoConstants.dat
PyroConstants.dat
VelocityOfSound.dat
If the strain option is activated, a folder Strain/
is created containing the strain tensor components $\epsilon_{ij}$ which are dimensionless.
Strain_CrystalSystem.dat
Strain_Simulation.dat
If the crystal has not been rotated, both files contain identical values.
The folder Polarization/
contains the piezoelectric and pyroelectric polarization if these options are activated.
PiezoChargeDensity.dat
PyroChargeDensity.dat
The folder Init_Electr_Modes/
contains 3 different folders corresponding to the different sets of basis states. They correspond to the initial solution of the Schrödinger equation without accounting for Poisson equation (i.e. electrostatic mean-field) nor scattering self-energies.
The folder Init_Electr_Modes/ReducedRealSpace/
contains:
ReducedRealSpaceModes.dat
RealSpaceModesOn.dat
H0RealSpace.txt
The folder Init_Electr_Modes/Wannier-Stark_States/
shows the eigenstates of the Schrödinger equation. In this folder, a default potential drop per period is taken as 1/2 of the <Energy_Range_Axial> specified in the input file. Otherwise it can be specified in the input file using the command <Bias_for_initial_Electronic_Modes>
in the <Simulation_Parameter>
section.
It contains:
Effective_masses.dat
Miniband #
Effective mass in the well [m0]
Effective mass in the barrier [m0]
Wannier-Stark_Energy_Separation.dat
Wannier-Stark_levels.dat
This file contains the conduction band edge and the probability densities.Wannier-Stark_levelsOn.dat
This file contains the conduction band edge and the probability densities. Points where the probability density is almost zero are omitted.
The Tight-binding folder contains data only if one or several <Analysis_Separator>
are defined in the input file. The tight-binding basis corresponds to piecewise solution of the Schrödinger equation between these separators.
Lateral_spectrum.dat
gives the energy discretization for the states used to describe the motion in the directions (x,y) perpendicular to the heterostructure. The lateral motion is discretized using cylindrical boundary conditions, and the corresponding eigenstates are Bessel funcitons. Lateral state index
order of Bessel
(zero index)-1 of Bessel
Relative Energy (meV)
.For each voltage, the following files are produced.
BandEdge_conduction.dat
Electrostatic-Potential_vs_position.dat
CarrierDensity.dat
Current-Density.dat
Current-miscellaneous.txt
WannierStark_Energy_Separation.dat
EnergySpacing.dat
for a particular voltage.Wannier-Stark_levels.dat
EnergyLevel_Absolute.dat
for a particular voltage.)Wannier-Stark_levelsOn.dat
Convergence.txt
NO-CONVERGENCE.txt
The folder 2D_Plots_Position-nm_Energy-eV/
contains files where the $x$ axis is position in [nm] and the $y$ axis is energy in units of [eV].
Note that these 2D plots show 2 QCL periods although only 1 period is simulated.
DOS.fld
/ *.coord
/ *.dat
Carrier_Density.fld
/ *.coord
/ *.dat
Current_Density.fld
/ *.coord
/ *.dat
The folder Gain/
contains files where the $x$ axis is position in [nm] and the $y$ axis is photon energy $E_{\rm ph}$ in units of [eV].
Note that these 2D plots show 2 QCL periods although only 1 period is simulated.
Energy-Resolved_Gain_Simple-Approximation.fld
/ *.coord
/ *.dat
Gain_Simple-Approximation.dat
Gain_SelfConsistent.dat
A negative value of gain corresponds to absorption.
Note that the gain output is only done for the voltages specified in the input file.
<!-- Calculate gain only between the following values of potential drop per period in order to save CPU time --> <Vmin unit="mV"> 160 </Vmin> <Vmax unit="mV"> 400 </Vmax>
The folder GreenFunctions/
contains information on the Green's functions.
The electron density $n(x,E_x)$ is related to the lesser Green's function $\mathbf{G}^<$ (“G lesser”): $$n(x,E_x) = - \frac{{\rm i}}{2\pi} \mathbf{G}(x,x^\prime=x,E_x)$$
GreenLesser_All.dat
GreenLesser_Z.dat
The local density of states $\rho(x,E_x)$ is related to the spectral function $\mathbf{A}$: $$\rho(x,E_x) = \frac{1}{2\pi} \mathbf{A}(x,x^\prime=x,E_x)$$ $\mathbf{A}$ is defined as $\mathbf{A} = {\rm i} (\mathbf{G}^{\rm R} - \mathbf{G}^{{\rm R}\dagger}) = - 2 {\rm Im}(\mathbf{G}^{\rm R})$. $\mathbf{G}^{\rm R}$ is the retarded Green's function.
GreenSpectral_All.dat
<Emin_shift unit="meV">
can be increased (by 200 meV) to reduce the calculation time. Essentially, the energy range of the Green's functions is altered by adjusting <Emin_shift unit=meV>
and <Emax_shift unit=meV>
.GreenSpectral_Z.dat
The folder DensityMatrix/
contains the density matrix $\rho$ which is a complex quantity and it is dimensionless.
The trace of the density matrix equals 1.
In our case, the trace is 1 if we sum over one period.
The state labels (state $i$, period $j$) are specified in the complex density matrix.
$$\rho(i,j) = \rho({\rm state},{\rm period})$$
DensityMatrix_complex.mat
DensityMatrix_RealPart_AbsoluteValue.mat
DensityMatrix_ImaginaryPart_AbsoluteValue.mat
For each simulation, the following files are produced.
Energy_WannierStarkStates.dat
Gain_vs_Voltage.dat
and Gain_vs_EField.dat
Current_vs_Voltage.dat
and Current_vs_EField.dat
Current-Density.dat
.