Abstract: This paper describes the drift-diffusion theory of the bipolar field-effect transistor (BiFET) with two identical and connected metal-oxide-silicon-gates (MOS-gates) on a thin-pure-base.Analytical solution is obtained by partitioning the two-dimensional transistor into two one-dimensional problems coupled by the parametric surface-electric-potential.Total and component output and transfer currents and conductances versus D.C.voltages from the drift-diffusion theory,and their deviations from the electrochemical (quasi-Fermi) potential-gradient theory,are presented over practical ranges of thicknesses of the silicon base and gate oxide. A substantial contribution from the longitudinal gradient of the square of the transverse electric field is shown.

Key words: bipolar field-effect transistor theory, MOS field-effect transistor, simultaneous electron and hole surface and volume channels, surface potential, longitudinal gradient of transverse electric field, 横向电场的纵向梯度