Radiation Sensitive Field Effect Transistors Research Articles

A design solution to increasing the sensitivity of pMOS dosimeters: the stacked RADFET approach

pMOS radiation sensitive field effect transistors (RADFET's) have applications as integrating dosimeters in spacecraft, laboratories and medicine to measure the amount of radiation dose absorbed. The suitability of these dosimeters to a certain application depends on the sensitivity 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 sensitivities to be achieved than is currently possible. An additional attractive feature of this design approach is that the sensitivity of the dosimeter may be changed depending on the total dose which is to be measured; essentially a dosimeter with auto-scaling may be achieved. This study introduces this auto-scaling concept along with presenting the optimum RADFET device requirements which are necessary for this new design approach. >

Investigation into the re-use of PMOS dosimeters

Radiation sensitive field effect transistors have applications as integrating dosimeters in spacecraft, laboratories and medicine to measure the amount of, radiation dose absorbed. However these dosimeters can measure only to a maximum dose which is determined by the type and sensitivity of the RADFET being used. On reaching the maximum radiation dose these dosimeters are usually replaced. The aim of this paper is to investigate the possibility of reusable dosimeters which to-date has not been addressed in the published literature. This study examines the response of dosimeters which were irradiated, annealed back to their original pre-irradiation threshold voltage and then irradiated for a second time. The results of the second irradiation suggest that reusing PMOS dosimeters is a feasible option.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The effect of gate-oxide process variations on the long-term fading of PMOS dosimeters

Abstract Radiation-sensitive field-effect transistors (RADFETs) have applications as integrating dosimeters in spacecraft, medicine and laboratories to measure the amount of dose absorbed from various radiation sources. The principal advantages that the RADFET has over more traditional forms of dosimeters is that it is small and provides continuous readout. However, all dosimetric media undergo some annealing or fading subsequent to irradiation. Fading effects in PMOS dosimeters may be negative or positive, depending on the occurrence of reverse annealing. The aim of this paper is to examine the effect of gate-oxide process variations on the long-term fading of the NMRC's PMOS dosimeter which has a dry/wet/dry gate oxide. The necessity for this evaluation arises because existing published results do not address the fading characteristics of dry/wet/dry oxides in the range 100–1000 nm. This paper clearly shows that for the NMRC's RADFET gate oxide an optimum set of processing conditions exists to minimize the dosimeter fading. The optimum processing conditions for fade reduction are compared with those required to maximize the radiation sensitivity of the dosimeter and the implications of fading at high dosimeter operating temperatures are discussed.