Materials{ }¶

Calling sequence

Materials{ }

Functionality

Defines the materials to be used in the heterostructure and specifies common settings for all materials.

Example

Materials{
    Material{
        ...
    }

    NumberOfBands = 3
    UseConductionBandOffset = yes
    NonParabolicity =
    NonParabolicityRelative =
    InPlaneNonParabolicity =
    TemperatureDependentEightBandDKKParameters = no
    ValleyDegeneracy =
}

Material{ }¶

Calling sequence

Materials{ Material{ } }

Functionality

Defines alias, alloy composition, and parameter settings of each material.

Example

Materials{
    Material{
        Name = GaAs
        Alias = "well"

        EffectiveMassFromKpParameters = yes
    }

    Material{
        Name = "Al(x)Ga(1-x)As"
        AlloyComposition = 0.15
        Alias = "barrier1"

        EffectiveMassFromKpParameters = yes
    }

    Material{
        Name = "Al(x)In(y)Ga(1-x-y)N"
        AlloyComposition = [0.16, 0.04]
        Alias = "well"

        EffectiveMassFromKpParameters = yes
        RescaleS = yes
    }
}

Material{ Name }¶

Calling sequence

Material{ Name }

Properties

type: \(\mathrm{character\;string}\)

Functionality

Specifies the material by the names defined in the database.

Material{ AlloyComposition }¶

Calling sequence

Material{ AlloyComposition }

Properties

type: \(\mathrm{real\;number}\)
type: \(\mathrm{vector\;of\;2\;real\;numbers}\)

Functionality

Specifies the alloy content of ternaries (scalar value) and quaternaries (2-dimensional vector).

Material{ Alias }¶

Calling sequence

Material{ Alias }

Properties

type: \(\mathrm{character\;string}\)

Functionality

Defines an alias used to refer to the material in the following of the input file.

Material{ EffectiveMassFromKpParameters }¶

Calling sequence

Material{ EffectiveMassFromKpParameters }

Properties

choices: yes; no

Functionality

If yes, the effective mass for the material will be calculated from the \(\mathbf{k} \cdot \mathbf{p}\) parameters in the database. If no, the electron mass will be taken from ElectronMass in the database.

Material{ RescaleS }¶

Calling sequence

Material{ RescaleS }

Properties

type: \(\mathrm{choice}\)
choices: yes; no
default: yes

Functionality

If yes, rescale the \(S = 1 + 2F\) parameter, where \(F\) is the remote-band contribution. See Electronic band structure for details.

Example

Materials{
    Material{
        Name = "In(x)Ga(1-x)As"
        ...
        EffectiveMassFromKpParameters = yes
        RescaleS = yes
        RescaleSTo = 1.0
    }
}

In the above example, rescaling \(S\) to 1 means that only the free electron kinetic energy term will remain (i.e. no remote-band contribution, \(F=0\)).

Material{ RescaleSTo }¶

Calling sequence

Material{ RescaleSTo }

Properties

type: \(\mathrm{real\;number}\)
default: 0

Functionality

Specifies the target value for Material{ RescaleS }.

Material{ Overwrite{ } }¶

Calling sequence

Material{ Overwrite{ } }

Functionality

Directly overwrites any parameters of binary, ternary, and quaternary alloys calculated from the database using the composition specified by Material{ AlloyComposition }. For available parameters inside this group, see Material Database and Material_Database.negf included in the installation package.

Example

Materials{
    Material{
        Name = GaAs
        Alias = "well"
        EffectiveMassFromKpParameters = no

        Overwrite{
            ConductionBandOffset = 0.0
            ElectronMass = 0.07
        }
    }

    Material{
        Name = "Al(x)Ga(1-x)As"
        AlloyComposition = 0.15
        Alias = "barrier"
        EffectiveMassFromKpParameters = no

        Overwrite{
            ConductionBandOffset = 0.135
            ElectronMass = 0.08
        }
    }
}

Note

Overwrite{} has higher priority than OverwriteMaterialdatabase{ }. Also note that Overwrite{} will overwrite directory the material parameters of an alloy for the composition specified in the input file, while OverwriteMaterialdatabase{ } will overwrite the bowing parameters.

NumberOfBands¶

Calling sequence

Material{ NumberOfBands }

Properties

type: \(\mathrm{integer}\)

Functionality

Specifies the model to be used for the Schrödinger equation. See Electronic band structure for model details.

UseConductionBandOffset¶

Calling sequence

Material{ UseConductionBandOffset }

Properties

type: \(\mathrm{choice}\)
choices: yes; no

Functionality

If yes, then the conduction band offsets as defined in the database file or overwritten in the input file are used. If no, then the conduction band offsets are calculated from the valence band offsets, split-off energies and temperature-dependent band gaps. This corresponds to the implementation of the nextnano++ software.

Note

The conduction band offsets get an additional shift if strain is present.

NonParabolicity¶

Calling sequence

Material{ NonParabolicity }

Properties

type: \(\mathrm{choice}\)
choices: yes; no

Functionality

no = parabolic effective mass: The effective mass \(m\) is independent of energy. This simple model can be sufficient for heterostructures with small conduction band offsets with respect to their bandgaps.

yes = nonparabolic effective mass: The effective mass \(m(E)\) depends on energy \(E\). This is more realistic model and is recommended in general. This model requires iteratively solving the Schrödinger equation in contrast to the parabolic model.

See Electronic band structure for model details.

NonParabolicityRelative¶

Calling sequence: Material{ NonParabolicityRelative }
Properties: …
Functionality: …

InPlaneNonParabolicity¶

Calling sequence

Material{ InPlaneNonParabolicity }

Properties

type: \(\mathrm{choice}\)
choices: yes; no

Functionality

If yes, consider in-plane nonparabolicity in the multiband models. See Electronic band structure for model details.

TemperatureDependentEightBandDKKParameters¶

Calling sequence

Material{ TemperatureDependentEightBandDKKParameters }

Properties

type: \(\mathrm{choice}\)
choices: yes; no
default: no

Functionality

…

ValleyDegeneracy¶

Calling sequence

Material{ ValleyDegeneracy }

Properties

type: \(\mathrm{integer}\)

Functionality

…