Controllable semiconductor devices

Claim 1

A SEMICONDUCTOR DEVICE COMPRISING, FIRST, SECOND AND THIRD TERMINALS, FIRST, SECOND AND THIRD CONTIGUOUS SEMICONDUCTOR REGIONS, ADJACENT REGIONS BEING OF OPPOSITE CONDUCTIVITY TO DEFINE A FIRST RECTIFYING JUNCTION PORTION BETWEEN SAID FIRST AND SECOND REGIONS AND A SECOND RECTICYING JUNCTION PORTION BETWEEN SAID SECOND AND THIRD REGIONS WITH SAID FIRST AND SECONF RECTIFCYING JUNCTION PORTIONS POLARIZED IN OPPOSITE SENSE, SAID FIRST AND SECOND RECTIFYING JUNCTION PORTIONS BEING IN SERIES BETWEEN SAID FIRST AND SECOND TERMINALS, A FOURTH SEMICONDUCTOR REGION OF THE SAME TYPE CONDUCTIVELY AS SAID SECOND REGION ADJACENT TO SAID THIRD REGION AND SAID THIRD TERMINAL AND DEFINING WITH SAID THIRD REGION A THIRD RECTIFYING JUNCTION PORTION IN SERIES WITH SAID FIRST AND SECOND RECTIFYING JUNCTION PORTIONS BETWEEN SAID FIRST AND THIRD TERMINALS WITH SAID FIRST AND THIRD RECTIFYING JUNCTION PORTIONS POLARIZED IN THE SAME SENSE, MEANS INCLUDING SAID FOURTH REGION AND MEANS INTERCOUPLING SAID SECOND AND FOURTH REGIONS ESTABLISHING A CARRIER CONDUCTION PATH FROM SAID THIRD TERMINAL FOR EXERCISING CONTROL OVER THE SECOND TERMINAL CURRENT AND FOR ESTABLISHING A NEGATIVE RESISTANCE CHAR-