Analysis of the MOS transistor based on the self-consistent solution to the Schrodinger and Poisson equations and on the local mobility model

The effects of carrier energy quantization in the semiconductor surface region on performance of the metal-oxide-semiconductor (MOS) transistor are theoretically considered by comparison of results of a self-consistent solution to the Schrodinger and Poisson equations and the results of the classical description. The gate voltage dependencies of the surface potential and inversion layer charge density are compared. Using the local mobility model the relations between the electron effective mobility and the electric effective field obtained from the both descriptions are for the first time compared. The accuracy of the commonly used triangular well approximation is examined. This approximation is used for calculation of the transistor current-voltage (I-V) characteristics. Simulations are performed for MOS transistors with ultrathin oxides and highly doped substrates, in accordance with the state of the art of today's VLSI/ULSI technology.