Scattering{ }

Calling sequence

Scattering{ ... }

Functionality

Specifies the setting for scattering calculation. See Scattering mechanisms for model description.

Dependencies

Depending on ScreeningTemperatureType, Exactly one of TemperatureOffsetParameter, AccuracySelfConsistentElectronTemperature, ElectronTemperatureForScreening must be defined.

Example

Scattering{
    MaterialForScatteringParameters = "well"

    InterfaceRoughness{
        AmplitudeInZ = 0.06                  # unit = nm
        InterfaceAutoCorrelationType = "exp"
        CorrelationLengthInXY = 8            # unit = nm
    }

    AlloyScattering = yes
    ElectronElectronScattering = no
    ScreeningTemperatureType = "offset"
    TemperatureOffsetParameter = 100

    # Tuning scattering strength
    ImpurityScatteringStrength = 1.0
    LOPhononCouplingStrength = 1.0
    AlloyScatteringStrength = 0.5
}

The following keywords are available within this group:

The following subgroups of keywords are available within this group:

MaterialForScatteringParameters

Calling sequence

Scattering{ MaterialForScatteringParameters = }

Properties

type: character string.
The string value has to match one of the alias defined in Material{ Alias }

Functionality

Selects a material that will be used to define the parameters used in the calculation of phonon scattering. The main material (e.g. used for the wells) of the structure can be chosen. An alloy material corresponding to the averaged alloy composition in the structure can also be defined and used here.

AcousticPhononScattering

Calling sequence

Scattering{ AcousticPhononScattering = }

Properties

values: yes or no
default: no

Functionality

If yes, calculate acoustic phonon scattering

Note

Acoustic phonon scattering is not efficient in general - can be neglected in most cases.

AcousticPhononScatteringEnergyMax

Calling sequence

Scattering{ AcousticPhononScatteringEnergyMax = }

Properties

type: real number

Functionality

Sets the maximum acoustic phonon energy.

LOPhononCouplingStrength

Calling sequence

Scattering{ LOPhononCouplingStrength = }

Properties

type: real number
values: [0.0, ...)

Functionality

Reduce (< 1.0) or enhance (> 1.0) LO-phonon scattering strength with respect to its microscopic calculation. The LO-phonon self-energy is multiplied by this factor. A value of 1.0 has no effect.

LOPhononDeformationPotential

Calling sequence

Scattering{ LOPhononDeformationPotential = }

Properties

values: yes or no
default: no

Functionality

If yes, calculate coupling to LO-phonon through optical deformation potential. Should be only used for nonpolar materials of the group IV.

ScreeningTemperatureType

Calling sequence

Scattering{ ScreeningTemperatureType = }

Properties

type: integer
type: character string

Functionality

Choose the model for effective temperature of the electrons involved in screening of Coulomb scattering. See Charged impurity scattering for the model description.

1 or offset : Use a phenomenological offset between the lattice and screening temperatures defined by \(T_{\text{screening}} = T_{\text{lattice}} + T_{\text{offset}} \exp{\left( - T_{\text{lattice}} / T_{\text{offset}} \right)}\) where \(T_{\text{lattice}}\) is the lattice temperature and \(T_{\text{offset}}\) is specified by the command TemperatureOffsetParameter

2 or self : Calculate the screening temperature \(T_{\text{screening}}\) in a self-consistent way (multiple NEGF iterations required).

3 or direct : Directly specify the temperature for screening \(T_{\text{screening}}\)

TemperatureOffsetParameter

Calling sequence

Scattering{ TemperatureOffsetParameter = }

Properties

type: real number
values: [0.0, ...)

Functionality

Specifies the offset temperature \(T_{\text{offset}}\) when the phenomenological offset is chosen in ScreeningTemperatureType

AccuracySelfConsistentElectronTemperature

Calling sequence

Scattering{ AccuracySelfConsistentElectronTemperature = }

Properties

type: real number
values: [0.0, ...)

Functionality

Specifies the target relative accuracy when self is used for ScreeningTemperatureType

ElectronTemperatureForScreening

Calling sequence

Scattering{ ElectronTemperatureForScreening = }

Properties

type: real number
values: [0.0, ...)

Functionality

Specifies the temperature for screening \(T_{\text{screening}}\) when direct is used for ScreeningTemperatureType

ImpurityScatteringStrength

Calling sequence

Scattering{ ImpurityScatteringStrength = }

Properties

type: real number
default: \(r=1.0\)

Functionality

Reduce (< 1.0) or enhance (> 1.0) impurity scattering strength with respect to its microscopic calculation. The impurity self-energy is multiplied by this factor. A value of 1.0 has no effect.

AlloyScattering

Calling sequence

Scattering{ AlloyScattering = }

Properties

values: yes or no
default: no

Functionality

If yes, consider scattering due to alloy disorder. See Alloy scattering for the model description.

AlloyScatteringStrength

Calling sequence

Scattering{ AlloyScatteringStrength = }

Properties

type: real number
values: [0.0, ...)

Functionality

Reduce (< 1.0) or enhance (> 1.0) alloy scattering strength with respect to its microscopic calculation. The alloy self-energy is multiplied by this factor. A value of 1.0 has no effect.

SeparateScattering

Calling sequence

Scattering{ SeparateScattering = }

Properties

values: yes or no
default: no

Functionality

If yes, calculate and output separately the retarded self-energy associated with LO-phonons

ElectronElectronScattering

Calling sequence

Scattering{ ElectronElectronScattering = }

Properties

values: yes or no
default: no

Functionality

If yes, consider electron-electron scattering

HomogeneousCoulomb

Calling sequence

Scattering{ HomogeneousCoulomb = }

Properties

values: yes or no
default: no

Functionality

Approximates the calculation of Coulomb scattering (impurities and electron-electron) by spatially homogeneous densities along the device.

CoarseGridCoulomb

Calling sequence

Scattering{ CoarseGridCoulomb = }

Properties

values: yes or no
default: yes

Functionality

If yes, compute Coulomb scattering matrix elements on a coarse grid corresponding to the reduced real space basis (default). If no, compute Coulomb scattering matrix elements on a fine grid corresponding to the full real space basis (computationally more intensive).

ElectElectScatteringStrength

Calling sequence

Scattering{ ElectElectScatteringStrength = }

Properties

type: real number
default: \(r=1.0\)

Functionality

Reduce (< 1.0) or enhance (> 1.0) electron-electron scattering strength with respect to its microscopic calculation. The electron-electron self-energy is multiplied by this factor. A value of 1.0 has no effect.

PhononDamping

Calling sequence

Scattering{ PhononDamping = }

Properties

type: real number
unit: \(\mathrm{meV}\)

Functionality

Specifies the intrinsic linewidth of transverse optical phonons due to anharmonicity (phonon-phonon scattering). The value is specified at 0K. The temperature dependence assumed decomposition of two acoustic phonons of equal energies. Please see Gain/absorption calculation from NEGF linear response theory for the model description.

Example

Scattering{
    PhononDamping = 2.0e-5  # Unit = eV
}

InterfacesCutOff

Calling sequence

Scattering{ InterfacesCutOff = }

Properties

type: integer

Functionality

Renormalize long-range Coulomb interaction to avoid spurious broadening effects. The range is specified in terms of a number of interfaces. For example 2 means that all inter-well Coulomb interactions are renormalized, while intra-Coulomb interactions are treated normally.

AugerCoefficient

Calling sequence

Scattering{ AugerCoefficient = }

Properties

type: real number
unit: \(\mathrm{cm^6/s}\)

Functionality

Coefficient of the classical model of Auger recombination rate \(Cnnp\) and \(Cnpp\), where \(n\) and \(p\) are local electron and hole densities, respectively. The \(n\)-type and \(p\)-type Auger coefficients are assumed to be the same (cf. Review paper on interband cascade lasers). Only relevant if NumberOfBands is 8 and valence band states are selected.

Last update: 28/01/2026