# PLaSK User Manual

#### Page Contents

- FreeCarrier3D Class
  - `FreeCarrier3D`
  - Subclasses
  - Methods
  - Attributes
    - Receivers
    - Providers
    - Other
  - Descriptions
    - Method Details
      - `FreeCarrier3D.get_energy_levels()`
      - `FreeCarrier3D.get_fermi_levels()`
      - `FreeCarrier3D.initialize()`
      - `FreeCarrier3D.invalidate()`
      - `FreeCarrier3D.spectrum()`
    - Receiver Details
      - `FreeCarrier3D.inBandEdges`
      - `FreeCarrier3D.inCarriersConcentration`
      - `FreeCarrier3D.inFermiLevels`
      - `FreeCarrier3D.inTemperature`
    - Provider Details
      - `FreeCarrier3D.outEnergyLevels`
      - `FreeCarrier3D.outGain`
    - Attribute Details
      - `FreeCarrier3D.T0`
      - `FreeCarrier3D.geometry`
      - `FreeCarrier3D.id`
      - `FreeCarrier3D.initialized`
      - `FreeCarrier3D.lifetime`
      - `FreeCarrier3D.matrix_element`
      - `FreeCarrier3D.strained`

# FreeCarrier3D Class

class gain.freecarrier.FreeCarrier3D(name='')

  Quantum-well gain using free-carrier approximation for three-dimensional Cartesian geometry.

## Subclasses

`Spectrum` | Gain spectrum object.

## Methods

`get_energy_levels`([T]) | Get energy levels in quantum wells.
`get_fermi_levels`(n[, T, reg]) | Get quasi Fermi levels.
`initialize`() | Initialize solver.
`invalidate`() | Set the solver back to uninitialized state.
`spectrum`(...) | Get gain spectrum at given point.

## Attributes

### Receivers

`inBandEdges` | Receiver of the conduction and valence band edges required for computations [eV].
`inCarriersConcentration` | Receiver of the carriers concentration required for computations [1/cm³].
`inFermiLevels` | Receiver of the quasi-Fermi levels for electrons and holes required for computations [eV].
`inTemperature` | Receiver of the temperature required for computations [K].

### Providers

`outEnergyLevels` | Provider of the computed energy levels for electrons and holes [eV].
`outGain` | Provider of the computed material gain [1/cm].

### Other

`T0` | Reference temperature.
`geometry` | Geometry provided to the solver
`id` | Id of the solver object.
`initialized` | True if the solver has been initialized.
`lifetime` | Average carriers lifetime.
`matrix_element` | Momentum matrix element.
`strained` | Boolean attribute indicating if the solver should consider strain in the active region.

## Descriptions

### Method Details

FreeCarrier3D.get_energy_levels(T=None)

  Get energy levels in quantum wells.

  Compute energy levels in quantum wells for electrons, heavy holes and light holes.

  Parameters:

    T (float or `None`) – Temperature to get the levels. If this argument is `None`, the estimates for temperature `T0` are returned.

  Returns:

    List with dictionaries with keys el, hh, and lh with levels for

      electrons, heavy holes and light holes. Each list element corresponds to one active region.

  Return type:

    list

FreeCarrier3D.get_fermi_levels(n, T=None, reg=0)

  Get quasi Fermi levels.

  Compute quasi-Fermi levels in specified active region.

  Parameters:

    - n (float) – Carriers concentration to determine the levels for (1/cm3).

    - T (float or `None`) – Temperature to get the levels. If this argument is `None`, the estimates for temperature `T0` are returned.

    - reg (int) – Active region number.

  Returns:

    Two-element tuple with quasi-Fermi levels for electrons and holes.

  Return type:

    tuple

FreeCarrier3D.initialize()

  Initialize solver.

  This method manually initialized the solver and sets `initialized` to True. Normally calling it is not necessary, as each solver automatically initializes itself when needed.

  Returns:

    solver `initialized` state prior to this method call.

  Return type:

    bool

FreeCarrier3D.invalidate()

  Set the solver back to uninitialized state.

  This method frees the memory allocated by the solver and sets `initialized` to False.

FreeCarrier3D.spectrum(point)
FreeCarrier3D.spectrum(c0, c1, c2)

  Get gain spectrum at given point.

  Parameters:

    - point (vec) – Point to get gain at.

    - c0 (float) – Coordinates of the point to get gain at.

    - c1 (float) – Coordinates of the point to get gain at.

  Returns:

    Spectrum object.

  Return type:

    `FreeCarrier3D.Spectrum`

### Receiver Details

FreeCarrier3D.inBandEdges = <property object>

  Receiver of the conduction and valence band edges required for computations [eV].

  You will find usage details in the documentation of the receiver class `BandEdgesReceiver3D`.

  Example

  Connect the receiver to a provider from some other solver:

      >>> solver.inBandEdges = other_solver.outBandEdges

  See also

  Receciver class: `plask.flow.BandEdgesReceiver3D`

  Provider class: `plask.flow.BandEdgesProvider3D`

  Data filter: `plask.filter.BandEdgesFilter3D`

FreeCarrier3D.inCarriersConcentration = <property object>

  Receiver of the carriers concentration required for computations [1/cm³].

  You will find usage details in the documentation of the receiver class `CarriersConcentrationReceiver3D`.

  Example

  Connect the receiver to a provider from some other solver:

      >>> solver.inCarriersConcentration = other_solver.outCarriersConcentration

  See also

  Receciver class: `plask.flow.CarriersConcentrationReceiver3D`

  Provider class: `plask.flow.CarriersConcentrationProvider3D`

  Data filter: `plask.filter.CarriersConcentrationFilter3D`

FreeCarrier3D.inFermiLevels = <property object>

  Receiver of the quasi-Fermi levels for electrons and holes required for computations [eV].

  You will find usage details in the documentation of the receiver class `FermiLevelsReceiver3D`.

  Example

  Connect the receiver to a provider from some other solver:

      >>> solver.inFermiLevels = other_solver.outFermiLevels

  See also

  Receciver class: `plask.flow.FermiLevelsReceiver3D`

  Provider class: `plask.flow.FermiLevelsProvider3D`

  Data filter: `plask.filter.FermiLevelsFilter3D`

FreeCarrier3D.inTemperature = <property object>

  Receiver of the temperature required for computations [K].

  You will find usage details in the documentation of the receiver class `TemperatureReceiver3D`.

  Example

  Connect the receiver to a provider from some other solver:

      >>> solver.inTemperature = other_solver.outTemperature

  See also

  Receciver class: `plask.flow.TemperatureReceiver3D`

  Provider class: `plask.flow.TemperatureProvider3D`

  Data filter: `plask.filter.TemperatureFilter3D`

### Provider Details

FreeCarrier3D.outEnergyLevels(n=0, mesh, interpolation='default') = <property object>

  Provider of the computed energy levels for electrons and holes [eV].

  Parameters:

    - n (int) – Value number.

    - mesh (mesh) – Target mesh to get the field at.

    - interpolation (str) – Requested interpolation method.

  Returns:

    Data with the energy levels for electrons and holes on the specified mesh [eV].

  You may obtain the number of different values this provider can return by testing its length.

  Example

  Connect the provider to a receiver in some other solver:

      >>> other_solver.inEnergyLevels = solver.outEnergyLevels

  Obtain the provided field:

      >>> solver.outEnergyLevels(0, mesh)
      <plask.Data at 0x1234567>

  Test the number of provided values:

      >>> len(solver.outEnergyLevels)
      3

  See also

  Provider class: `plask.flow.EnergyLevelsProvider3D`

  Receciver class: `plask.flow.EnergyLevelsReceiver3D`

FreeCarrier3D.outGain(n=0, mesh, lam, interpolation='default') = <property object>

  Provider of the computed material gain [1/cm].

  Parameters:

    - deriv (str) – Gain derivative to return. can be ‘’ (empty) or ‘conc’. In the latter case, the gain derivative over carriers concentration is returned.

    - mesh (mesh) – Target mesh to get the field at.

    - interpolation (str) – Requested interpolation method.

    - lam (float) – The wavelength at which the gain is computed (nm).

  Returns:

    Data with the material gain on the specified mesh [1/cm].

  You may obtain the number of different values this provider can return by testing its length.

  Example

  Connect the provider to a receiver in some other solver:

      >>> other_solver.inGain = solver.outGain

  Obtain the provided field:

      >>> solver.outGain(0, mesh, lam)
      <plask.Data at 0x1234567>

  Test the number of provided values:

      >>> len(solver.outGain)
      3

  See also

  Provider class: `plask.flow.GainProvider3D`

  Receciver class: `plask.flow.GainReceiver3D`

### Attribute Details

FreeCarrier3D.T0 = <property object>

  Reference temperature.

  In this temperature levels estimates are computed.

FreeCarrier3D.geometry = <property object>

  Geometry provided to the solver

FreeCarrier3D.id = <property object>

  Id of the solver object. (read only)

  Example

      >>> mysolver.id
      mysolver:category.type

FreeCarrier3D.initialized = <property object>

  True if the solver has been initialized. (read only)

  Solvers usually get initialized at the beginning of the computations. You can clean the initialization state and free the memory by calling the `invalidate()` method.

FreeCarrier3D.lifetime = <property object>

  Average carriers lifetime.

  This parameter is used for gain spectrum broadening. (float [ps])

FreeCarrier3D.matrix_element = <property object>

  Momentum matrix element.

  Value of the squared matrix element in gain computations. If it is not set it is estimated automatically. (float [eV×m0])

FreeCarrier3D.strained = <property object>

  Boolean attribute indicating if the solver should consider strain in the active region.

  If set to `True` then there must a layer with the role substrate in the geometry. The strain is computed by comparing the atomic lattice constants of the substrate and the quantum wells.