Recombination groups in database{ …_zb{} } and database{ …_wz{} }

There are about 23 identical groups available directly under all zincblende- and wurtzite-related groups. In this section we describe one of them, specifically the group related to recombination models recombination{}.

database{ …{ recombination{} } }

This section specifies the coefficients related to recombination processes. These are used when the current equation is solved. In nextnano++, the following recombination processes are included:

Example

binary_zb {
    name    = Si                        # material name, e.g. Si, GaAs, InP, ...

        ...

    recombination{
                                        # Shockley-Read-Hall recombination
        SRH{        tau_n  = 1.0e-9     # [s]    zero doping scattering time for electrons
                    nref_n = 1.0e19     # [cm^-3] reference doping concentration for electrons
                    tau_p  = 1.0e-9     # [s]    zero doping scattering time for holes
                    nref_p = 1.0e18     # [cm^-3] reference doping concentration for holes
        }

                                        # Auger recombination
        Auger{      c_n    = 2.8e-31    # [cm^6/s]
                    c_p    = 9.9e-31    # [cm^6/s]
        }

                                        # direct recombination
        radiative{  c = = 2.0e-10   }   # [cm^3/s]
                                        # 2.0e-10 for GaAs, 0 for Si (indirect semiconductor)

    }

}

Shockley-Read-Hall (SRH) recombination

tau_n

zero doping scattering time for electrons \(\tau_{n0}\) in the formula (2.8.1.1).

type:

double

unit:

s

nref_n

reference doping concentration for electrons \(N_{n,ref}\) in the formula (2.8.1.1).

type:

double

unit:

cm-3

tau_p

zero doping scattering time for holes \(\tau_{p0}\) in the formula (2.8.1.1).

type:

double

unit:

s

nref_p

reference doping concentration for holes and \(N_{p,ref}\) in the formula (2.8.1.1).

type:

double

unit:

cm-3

Auger recombination

c_n

coefficient \(C_n\) in the formula (2.8.1.2).

type:

double

unit:

cm6 s-1

c_p

coefficient \(C_p\) in the formula (2.8.1.2).

type:

double

unit:

cm6 s-1

Radiative recombination

c

a coefficient \(C\) in the formula (2.8.2.1).

type:

double

unit:

cm3 s-1

example:

2.0e-10 (for GaAs), 0.0 (for Si, indirect semiconductor)

c_absorption

If c_absorption > c, then c_absorption will be used instead of c as \(C\) to compute absorption coefficients in semiclassical optics. This can be used to enable and control absorption for indirect bandgap materials where c practically vanishes. Ideally, for these materials, c_absorption should be set in the database to values which reproduce the experimentally observed absorption coefficients.

type:

double

unit:

cm3 s-1

default:

1e-11

Last update: 2025-11-07