Generalized energy transport models for semiconductor device simulation

Abstract

Two systems of generalized equations are derived by applying the method of moments to an approximation of the Boltzmann transport equation for semiconductors, valid for general band structure. The equations of one of the resulting models are examined in detail and the presence of a convective term in the definition of the odd-order moments is highlighted. The energy transport models are obtained by truncating the system of equations at the third order moments. As a closure assumption, the coefficients of the models are computed numerically from homogeneous solutions of the expansion of the Boltzmann transport equation. The models are applied to a ballistic diode and the results are compared with those obtained from the solution of the expansion of the Boltzmann transport equation, showing a satisfactory agreement without any fitting of parameters. Finally, the simulation of an LDD-MOS transistor is presented and the results are compared with those obtained from a hydrodynamic model. A good agreement is found in this case as well. © 1994.