Voltage variable resistor

Claim 1

A FIELD-EFFECT DEVICE COMPRISING A WAFER OF MONOCRYSTALLINE SEMICONDUCTOR MATERIAL, A GATE REGION HAVING A NET DOPANT CONCENTRATION OF ONE TYPE CONDUCTIVITY DEFINED IN THE WAFER ADJACENT ONE MAJOR FACE THEREOF, AN OHMIC CONTACT ON SAID GATE REGION, A CHANNEL REGION HAVING A NET DOPANT CONCENTRATION OF OPPOSITE TYPE CONDUCTIVITY DEFINED IN THE WAFER ADJACENT SAID ONE MAJOR FACE AND UNDERLYING SAID GATE REGION, A PAIR OF OHMIC CONTACTS ON OPPOSITE ENDS OF THE CHANNEL REGION PROVIDING SOURCE AND DRAIN CONNECTIONS, MEANS INCLUDING A VOLTAGE SOURCE CONNECTED TO THE OHMIC CONTACT ON THE GATE REGION AND TO ONE OF SAID PAIR OF OHMIC CONTACTS TO APPLY A REVERSE VOLTAGE BETWEEN SAID GATE REGION AND SAID CHANNEL REGION, THE NET DOPANT CONCENTRATION IN SAID GATE REGION BEING LARGE RELATIVE TO THE NET DOPANT CONCENTRATION IN SAID CHANNEL REGION, SAID CHANNEL REGION HAVING MEANS INCLUDING A NET DOPANT CONCENTRATION GRADIENT DECREASING AWAY FROM SAID GATE REGION SUCH THAT IN RESPONSE TO SUC-