Quantum relaxation times and carrier transport parameters in gate-controlled semiconductor conduction channels

In the electron-electron collision dominated regime the hydrodynamic model can be used to study carrier transport in conduction channels of diamond-based Field Effect Transistors (FETs). In the hydrodynamic regime the parameters are quasi-particle lifetime determined by electron-electron scattering, momentum relaxation time due to electron-phonon and electron-impurity scatterings, and momentum diffusion time that characterizes the spread of the electron distribution in the k-space due to the electron-electron scattering. In high mobility FETs the shear viscosity and the in-channel thermal conductivity are important transport coefficients for the input to the TCAD modeling of FETs. We evaluate the viscosity of the gate-controlled electron or hole gas from the momentum diffusion time in the degenerate Fermi gas regime. The resulting temperature and density dependence of the shear viscosity in the non-gated limit is the same as was obtained elsewhere from solutions of the 2D linearized Boltzmann equation. We find that the shear viscosity is the dominant parameter to determine the high-frequency plasmonic response of high mobility FETs. In applying our results to the specific case of the transferred-doped diamond FET the relevant band parameters were found from DFT calculations.