Abstract: The field-effect transistor is inherently bipolar,having simultaneously electron and hole surface and volume channels and currents. The channels and currents are controlled by one or more externally applied transverse electric fields. It has been known as the unipolar field-effect transistor for 55-years since Shockley’s 1952 invention,because the electron-current theory inevitably neglected the hole current from over-specified internal and boundary conditions,such as the electrical neutrality and the constant hole-electrochemical-potential,resulting in erroneous solutions of the internal and terminal electrical characteristics from the electron channel current alone,which are in gross error when the neglected hole current becomes comparable to the electron current,both in subthreshold and strong inversion. This report presents the general theory,that includes both electron and hole channels and currents.The rectangular (x,y,z) parallelepiped transistors,uniform in the width direction (z-axis),with one or two MOS gates on thin and thick,and pure and impure base,are used to illustrate the two-dimensional effects and the correct internal and boundary conditions for the electric and the electron and hole electrochemical potentials. Complete analytical equations of the DC current-voltage characteristics of four common MOS transistor structures are derived without over-specification: the 1-gate on semi-infinite-thick impure-base (the traditional bulk transistor),the 1-gate on thin impure-silicon layer over oxide-insulated silicon bulk (SOI),the 1-gate on thin impure-silicon layer deposited on insulating glass (SOI TFT),and the 2-gates on thin pure-base (FinFETs).

Key words: bipolar field-effect transistor theory, MOS field-effect transistor, simultaneous electron and hole surface and volume channels and currents, surface potential, two-section short-channel theory, double-gate impure-base theory