Simulation of special features of the drift-mobility saturation in submicrometer silicon structures

Abstract

Special characteristics of the high-field drift of electrons in submicrometer n ⁺-n-n ⁺ structures are studied by mathematical simulation methods in the quasi-hydrodynamic approximation. Alternative dependences of the mobility and energy-relaxation time on the electron temperature are used to calculate the profiles of the potential, temperature, drift mobility, and density of the thermal-energy flux of electrons. It is shown that, in a submicrometer configuration, a large part of the thermal energy acquired by an electron in a high-resistivity n-type region is dissipated in a low-resistivity n ⁺-type contact. This effect reduces the rate of increase in the electron temperature in the drift region as the voltage increases, brings about an increase in the effective mobility, and prevents saturation of the drift velocity, as is shown by the calculated current-voltage characteristics.