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STUDY AND DEVELOPMENT OF MICROELECTRONIC DEVICES FOR RADIATION PROTECTION

Objective

THIS PROPOSAL WILL PROVIDE MORE INFORMATION DOSIMETRY FOR THE PROTECTION OF WORKERS AND THE POPULATION. PERSONAL DOSIMETRY WILL BE IMPROVED.
THE PROPOSED SUBJECT OF RESEARCH IS CENTERED UPON THE DEVELOPMENT OF MICROELECTRONIC DEVICES FOR THE PURPOSE OF DETECTION AND ANALYSIS OF IONIZING RADIATIONS AS ENCOUNTERED IN RADIATION PROTECTION APPLICATIONS. IT IS PROPOSED THAT DEVICES KNOWN AS EXPOSED GATE FIELD EFFECT TRANSISTORS (KNOWN ALSO AS OSFET-OXIDE-SILICON-FIELD-EFFECT-TRANSISTORS) ARE FABRICATED BOTH AD INITIO, AND ALSO FROM UNFINISHED PRODUCTS SUPPLIED BY THE MANUFACTURERS OF INTEGRATED CIRCUITS (E.G. SILICONIX, MOSTEK, TEXAS INSTRUMENTS, PLESSEY, ETC.). FABRICATION OF SUCH DEVICES FROM UNFINISHED PRODUCTS WILL INVOLVE CHEMICAL REMOVAL OF THE GATE MATERIAL AND/OR ION BEAM ETCHING. EXPOSED GATE FET'S (EGFET'S) ARE SENSITIVE TO PARTICLES ENTERING THE GATE DIELECTRIC. IT IS PROPOSED TO INVESTIGATE DETECTING PROPERTIES OF EGFET'S WITH GATE REGION COVERED BY AN ORGANIC FILM DEPOSITED BY EVAPORATION OR ELECTROPHORESIS AS WELL AS THE SAME OF DEVICE IMMERSED IN TISSUE EQUIVALENT LIQUID. THE EXAMINATION OF AN EGFET AS A DETECTION DEVICE WILL AIM AT FINDING THE FOLLOWING IMPORTANT INFORMATION:
- OPTIMUM DESIGN OF THE EGFET GEOMETRY
- OPTIMUM OPERATING POTENTIALS OF EGFET
- SENSITIVE VOLUME, DE/DX DISCRIMINATION
- USE OF EGFET WITH A POTENTIAL WELL OF VARYING SIZE AS A DEVICE FOR DINGING MICRODOSIMETRIC DISTRIBUTIONS
- RESPONSE OF EGFET, WITH DIFFERENT MATERIALS SURROUNDING THE GATE, TO X-RAYS, GAMMA RAYS, NEUTRONS AND ALPHA PARTICLES
- FABRICATION METHODS FOR EGFETS
- INTERFACING OF EGFETS TO MICROELECTRONIC AMPLIFIERS, DISCRIMINATORS, ETC.

A STUDY OF THE ROLE OF SMALL SCALE NON-EQUILIBRIUM CONDITIONS WILL BE CARRIED OUT USING BOTH EXPERIMENTAL TECHNIQUES WITH TLD AND LLD, AS WELL AS COMPUTATIONAL APPROACH, TO ELUCIDATE ITS INFLUENCE ON THE DATA PROVIDED BY THE SILICON BASE SENSORS. THIS INVESTIGATION WILL BE FOLLOWED BY THE TESTS WITH EGFETS USED AS RADIATION DETECTORS AND THE RESULTS COMPARED WITH THOSE OBTAINED IN MORE CONVENTIONAL WAY WITH THE USE OF GAS DETECTORS. THE FINAL OUTCOME, EXPECTED FROM THE PROPOSED RESEARCH WILL BE DEVELOPMENT OF PROTOTYPES OF RADIATION MEASURING AND INTERPRETING INSTRUMENTS, FOR THE USE IN RADIATION PROTECTION. CONSIDERATION WILL BE GIVEN TO THE PROBLEMS OF RELIABILITY, REPRODUCTIBILITY, PRICE, WEIGHT AND POWER CONSUMPTION OF THIS NEW TYPE OF MONITORING INSTRUMENTS.
MICROELECTRONIC TECHNOLOGY IS A NOVEL TECHNOLOGY, BASED ON THE PROGRESS WHICH TOOK PLACE IN THE SOLID STATE PHYSICS AND SOLID STATE TECHNOLOGY DURING THE LAST TWO DECADES. MICROELECTRONIC DEVICES HAVE ALMOST COMPLETELY REPLACED VACUUM DEVICE TECHNOLOGY IN THE ELECTRONIC APPLICATIONS, PARTICULARLY IN THE FIELD OF CONTROL, COMPUTING AND COMMUNICATIONS. MICROELECTRONICS IS USED IN THE SIGNAL PROCESSING IN RADIATION MONITORS AND IT IS A LOGICAL EXTENSION OF THE BENEFITS WHICH WERE REAPED FROM THE USE OF MICROELECTRONIC DEVICES IN THE SIGNAL CHAINS (EASE OF FABRICATION, SMALL SIZE, SMALL POWER CONSUMPTION, VERY HIGH RELIABILITY, PERFORMANCE OF "INTELLIGENT" FUNCTIONS, LOW COST PER UNIT) TO APPLY THE SAME TYPE OF TECHNOLOGY TO THE DESIGN AND FABRICATION OF MICROELECTRONIC RADIATION DETECTORS, WITH AN INTERNAL OR EXTERNAL IONIZATION LOSS ZONE, AS WELL AS TO THE INTEGRATION OF SUCH DETECTORS WITH THE HYBRID OR TRUE MICROELECTRONIC DEVICES FOR SIGNAL PROCESSING. THIS SHOULD RESULT IN AVAILABILITY OF VERY RELIABLE, VERY SMALL, ENERGY EFFICIENT AND DURABLE MEANS OF INDIVIDUAL RADIATION MONITORING, CAPABLE OF PROVIDING INFORMATION ON THE QUALITY OF RADIATION AS WELL AS ON THE RADIATION DOSE.
THERE ALSO EXISTS A DISTINCT POSSIBILITY THAT SUCH DEVICES MAY BE CAPABLE OF IMPLANTING INTO HUMAN TISSUES, E.G. INTO FINGERS AND PROVIDE AN ARTIFICIAL SENSE INPUT TO THE HUMAN NERVOUS SYSTEM. THE "MESSAGE" OF THIS KIND WOULD APPEAR AS TICKLING, LOCAL PAIN OR HEAT TO THE PERSON WHO HAS SUCH DEVICES IMPLANTED. THERE ARE NUMEROUS ADVANTAGES OF IMPLANTED RADIATION DETECTORS IN THE CASE OF RADIATION WORKERS, SPACE PERSONNEL AND OTHER CATEGORIES, LIKE MILITARY PERSONNEL.
DEVELOPMENT OF MODERN DEVICES FOR RADIATION DETECTION, MONITORING AND ANALYSIS, WHICH COULD BE SO CHEAP THAT ALL THE RADIATION WORKERS AND OTHER CATEGORIES OF STAFF AND PUBLIC MAY BE PROVIDED WITH THEM, AND SO RELIABLE AS TO MEET THE STRINGENT CRITERIA IMPOSED BY THE EEC LEGISLATION, WILL HELP TO PROVIDE THE TECHNOLOGICAL MEANS OF RADIATION PROTECTION AND WILL ALLEVIATE SOME OF THE PUBLIC ANXIETY ASSOCIATED WITH THE SUBJECT OF EXPOSURE TO IONIZING RADIATION. SUCH DEVICES COULD BE MANUFACTURED WITHIN THE EEC INDUSTRIAL BASE, BECAUSE THEY WILL BE JUST

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

University of Aberdeen
Address
Regent Walk
AB9 1FX Aberdeen
United Kingdom