2.13.4. insulator_bandgap

Calling sequence

currents{ insulator_bandgap }

Properties

• usage: \(\mathrm{\textcolor{ForestGreen}{optional}}\)

• type: real number

• unit: \(\mathrm{eV}\)

• values: [1e-6, ...)

• default: \(r=1.0\)

Functionality

This keyword, \(I_{\text{gap}}\), initializes the quasi-Fermi levels following the formula:

\[\text{div} \exp \left( E_{\text{gap}} / I_{\text{gap}} \right) \nabla E_{\text{F}} = 0,\]

where the intrinsic density is assumed to exponentially depend on the band gap \(E_{\text{gap}}\) with \(I_{\text{gap}}\) as a parameter.

A large value (relative to band gap) of \(I_{\text{gap}}\) allows the Fermi level to drop slowly through antire simulation domain. A small value of \(I_{\text{gap}}\) results in the quasi-Fermi levels drop rapidly in barriers and makes it flat in small band gap regions.

Adjusting this keyword can improve convergence by changing the initial conditions for the algorithm.

Example

currents{
    recombination_model{}
    insulator_bandgap = 0.5
}