# Graphene

Parametric surface conductivity model for graphene.

Select Graphene from the Material Library to add this parametric medium.

# Name

name: Optional unique name for the medium.

# Optical Properties

# Chemical Potential

mu_c: Chemical potential.

Type: floating-point number

  • Unit: eV
  • Default: 0

# Temperature

temp: Temperature.

Type: floating-point number

  • Unit: K
  • Constraint: greater than or equal to 0
  • Default: 300

# Scattering Rate

gamma: Scattering rate.

Type: floating-point number

  • Unit: eV
  • Constraint: greater than or equal to 0
  • Default: 0.00041

Note: Must be small compared to the optical frequency.

# Scaling Factor

scaling: Scaling factor used to model multiple layers of graphene.

Type: floating-point number

  • Unit: unitless
  • Default: 1

# Advanced

# Include Interband Terms

include_interband: Include interband terms, relevant at high frequency (IR). Otherwise, the intraband terms only give a simpler Drude-type model relevant only at low frequency (THz).

Type: boolean

  • Default: True

# Interband Frequency Nodes

interband_fit_freq_nodes: Frequency nodes for fitting interband term. Each pair of nodes in the list corresponds to a single Pade approximant of order (1, 2), which is optimized to minimize the error at these two frequencies. The default behavior is to fit a first approximant at one very low frequency and one very high frequency, and to fit a second approximant in the vicinity of the interband feature. This default behavior works for a wide range of frequencies; consider changing the nodes to obtain a better fit for a narrow-band simulation.

Type: floating-point pairs

  • Unit: THz
  • Constraint: greater than or equal to 0
  • Default: None (Tidy3D places the fitting nodes around the interband feature, which it computes from mu_c and temp)

# Interband Optimization Iterations

interband_fit_num_iters: Number of iterations for optimizing each Pade approximant when fitting the interband term. Making this larger might give a better fit at the cost of decreased stability in the fitting algorithm.

Type: integer

  • Unit: unitless
  • Constraint: greater than or equal to 0
  • Default: 100

# Appearance

Appearance settings control the medium’s face color and transparency in the model view. They do not change the optical properties.

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