Discrete power MOSFETs employ semiconductor processing techniques that are similar to those of today's VLS circuits, although the device geometry, voltage and current levels are significantly different from the design used in VLSI devices. The metal oxide semiconductor field effect transistor (MOSFET) is based on the original field-effect transistor introduced in the 70s.  Figure 1 shows the device schematic, transfer characteristics and device symbol for a MOSFET.  The invention of the power MOSFET was partly driven by the limitations of bipolar powe junction transistors (BJTs) which, until recently, was the device of choice in power electronics applications.Power MOSFET Basics.pdf