A DESIGN SOLUTION TO INCREASING THE SENSITIVITY OF PMOS DOSIMETERS - THE STACKED RADFET APPROACH

pMOS Radiation Sensitive Field Effect Transistors (RADFET's) have appl ications as integrating dosimeters in spacecraft, laboratories and med icine to measure the amount of radiation dose absorbed. The suitabilit y of these dosimeters to a certain application depends on the sensitiv ity of the RADFET being used. To date, this sensitivity is limited to the sensitivity of the gate oxide to radiation. The aim of this paper is to introduce a new design approach which will allow greater sensiti vities to be achieved than is currently possible. An additional attrac tive feature of this design approach is that the sensitivity of the do simeter may be changed depending on the total dose which is to be meas ured; essentially a dosimeter with auto-scaling may be achieved. This study introduces this autoscaling concept along with presenting the op timum RADFET device requirements which are necessary for this new desi gn approach.