currents{ insulator_bandgap }

• \(\mathrm{\textcolor{Aquamarine}{optional}}\)

• type: \(\mathrm{real\;number}\)

• unit: \(\mathrm{eV}\)

• values: \([10^{-6}, \ldots)\)

• default: \(1.0\)

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.