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 =
}

The following keywords are available within this group.

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

Materials{ Material{ Name } }

Properties

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

Functionality

Specifies the material by the names defined in Material Database.

Material{ AlloyComposition }

Calling sequence

Materials{ 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

Materials{ 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

Materials{ 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

Materials{ 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

Materials{ Material{ RescaleSTo } }

Properties

  • type: \(\mathrm{real\;number}\)

  • default: 0

Functionality

Specifies the target value for Material{ RescaleS }.

Material{ Overwrite{ } }

Calling sequence

Materials{ 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

Material{ Overwrite{ } } has higher priority than OverwriteMaterialdatabase{ }. Also note that Material{ 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

Materials{ 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

Materials{ UseConductionBandOffset }

Properties

  • type: \(\mathrm{choice}\)

  • choices: yes; no

Functionality

Switches between two options to define the band offsets:

  • If yes, then the conduction band offsets as defined in the database file or overwritten in the input file are used. The valence band offset is then calculated.

  • If no, then the valence band offsets as defined in the database file or overwritten in the input file are used. The conduction band offset is calculated from the valence band offsets, split-off energies and temperature-dependent band gaps using the (possibly overwritten) database parameters. This corresponds to the implementation of the nextnano++ software (see Definition of Band Offsets (zincblende)).

See Definition of band offsets for the model description.

NonParabolicity

Calling sequence

Materials{ 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

Materials{ NonParabolicityRelative }

Properties

  • type: \(\mathrm{real\;number}\)

Functionality

—

InPlaneNonParabolicity

Calling sequence

Materials{ 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

Materials{ TemperatureDependentEightBandDKKParameters }

Properties

  • type: \(\mathrm{choice}\)

  • choices: yes; no

  • default: no

Functionality

—

ValleyDegeneracy

Calling sequence

Materials{ ValleyDegeneracy }

Properties

  • type: \(\mathrm{integer}\)

Functionality

—