This paper is concerned with a new sub-threshold device configuration, the Schottky Junction Transistor (SJT). Results from measurements and numerical simulations of SJTs with gate lengths in the range 2 to 0.3 pm are presented. Detailed measurements of the d.c. characteristics of a 2 pm gate length device agree well with numerical simulations. Measurements of transconductance and gate capacitance suggest that this relatively long gate length, L, device will have a cut-off frequency 5-6 times higher that that of an equivalent metal oxide semiconductor field effect transistor (MOSFET) carrying the same current. When projected to gate lengths of 0.1 p, cut-off fi-equencies in excess of 10 GHz are predicted. Prototype devices made at ASU perform as expected from numerical simulations. The same devices have now been exposed to 50 keV x-rays at total doses up to 200 had. The paper will present an overview of the SJT and describe the recent total dose exposure measurements.