Theory of magnetic-field-sensitive metal-oxide-semiconductor field-effect transistors

Magnetic-field-sensitive metal-oxide-semiconductor field-effect transistors (MAGFETs) are used as magnetic field sensors. The Hall effect in the high-resistance channel region near the drain ensures a high magnetic field sensitivity of the transistor. In this case, the channel is nonuniform, and this fact presents difficulties when developing a Hall effect theory (the well-known theory of the Hall effect for uniform wafers is now inapplicable). Here, we propose a method that reduces the theory of galvanomagnetic effects in the MAGFETs with nonuniform channels to that for uniform wafers. Basing on this method, as well as on the conformal mapping and the Hall field symmetry, we calculate the Hall electromotive force in MAGFET channels with the Hall taps and split drain. The Hall current in MAGFETs with the split drain and split source is also obtained. It is shown that MAGFET magnetoresistance may be high. (C) 1999 American Institute of Physics. [S0021-8979(99)02703-6].