Temperature behaviour of electron mobility in double-gate silicon on insulator transistors

Abstract

We have studied the electron mobility behaviour in double-gate silicon on insulator (DGSOI) inversion layers as a function of temperature. It has been shown that as in the case of room temperature, volume inversion plays a very important role, being responsible for the enhancement of the electron mobility in a certain range of silicon thicknesses, Tw. Poisson's and Schrödinger's equations have been self-consistently solved to study the distribution of the electrons in DGSOI structures as a function of temperature. As in the room temperature case, volume inversion means that in the range of silicon thicknesses between 5 nm and 20 nm, the phonon-scattering rate is lower than the corresponding value for bulk silicon inversion layers. We have solved the Boltzmann transport equation by the Monte Carlo method, and have evaluated the electron mobility. For the whole range of temperatures we observed that for 5 nm < Tw < 20 nm, electron mobility in DGSOI devices, μDGSOI, is higher than the mobility for bulk silicon inversion layers, μbulk, and that the factor increases as the temperature decreases, i.e., the improvement of the mobility due to the volume inversion effect is more important at low temperatures than at room temperature.