Use of a Metal-Nitride-Oxide-Semiconductor as the Detector for a Radiation Dosimeter.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING
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A method of radiation dosimetry using a Metal-Nitride-Oxide-Semiconductor MNOS device as the detector was developed and partially evaluated. The MNOS devices are capable of measuring doses from 10 k rads to 4 M rads. Repeatability of observations indicates a precision of or - 1 of total dose from 200 k rads to 4M rads Si. Dosage in rads is obtained by reference to a calibrated source exposure rate and not to dose absorbed within the dosimeter. A Co60 source was used for all radiation testing. Schematics are given for some of the circuits tested. Determination of dosage from the system is indirect and requires the use of a calibration curve. Each dosimeter must be calibrated from a known source. Direct readout of dose is suggested by use of a microprocessor. Exposure to 20,000,000 rads did not degrade performance. Devices eventually failed due to charge migration from the large integrated circuit chip on which they were fabricated. Discrete, non-stepped gate MNOS transistors are recommended. Author
- Electrical and Electronic Equipment