Abstract: This paper describes the foundation underlying the device physics and theory of the semiconductor field effect transistor which is applicable to any devices with two carrier species in an electric field. The importance of the boundary conditions on the device current-voltage characteristics is discussed. An illustration is given of the transfer DCIV characteristics computed for two boundary conditions,one on electrical potential,giving much higher drift-limited parabolic current through the intrinsic transistor,and the other on the electrochemical potentials,giving much lower injection-over-the-barrier diffusion-limited current with ideal 60mV per decade exponential subthreshold roll-off,simulating electron and hole contacts.The two-MOS-gates on thin pure-body silicon field-effect transistor is used as examples.

Key words: bipolar field-effect transistor theory, MOS field-effect transistor, electric potential, electrochemical potential, boundary conditions