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Constant mobility model

More documentation on the constant mobility model ==> nextnano³ documentation

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

 ...

 mobility_constant{
   electrons{ mumax    = 1417    # µmax = bulk phonon mobility for electrons [cm2/Vs]
              exponent = 2.5  }  # temperature dependence exponent for electrons
   holes    { mumax    = 470.5   # µmax = bulk phonon mobility for holes [cm2/Vs]
              exponent = 2.2  }  # temperature dependence exponent for holes
 }
}

The constant mobility model is due to lattice scattering (phonon scattering) and leads to a constant mobility that depends only on the temperature T. The lattice atoms oscillate about their equilibrium sites at finite temperature leading to a scattering of carriers which results in a temperature dependent mobility µ_const. µ_max is the mobility due to bulk phonon (lattice) scattering. For all semiconductors the temperature dependent lattice mobility is modeled by a power law.

   µ_const(T) = µ_max (T/T₀)^-exponent

   T₀ = 300 K, T = temperature

The parameter values used in this model for electrons and holes, respectively, are taken from the PhD thesis of V. Palankovski "Simulation of Heterojunction Bipolar Transistors" (TU Vienna). (Note: The exponent has opposite sign in his PhD thesis.)