MeV Neutron Equivalent Fluence Research Articles

Shallow level analysis in irradiated silicon

Silicon p/sup +//n/n/sup +/ junctions with nominal starting resistivity of 4-6 k/spl Omega/cm have been irradiated with a 1 MeV neutron-equivalent fluence up to 4/spl middot/10/sup 14/ cm/sup -2/. In order to investigate the changes in the shallow level concentrations induced by irradiation, low temperature Thermally Stimulated Current measurements have been performed. For fluences over 10/sup 13/ cm/sup -2/ a phosphorous removal is observed, probably due to the formation of the vacancy-phosphorous complex.

Evaluation of GaAs low noise and power MMIC technologies to neutron, ionizing dose and dose rate effects

An evaluation programme of Thomson CSF-TCS GaAs low noise and power MMIC technologies to 1 MeV equivalent neutron fluence levels, up to 1/spl times/10/sup 15/ n/cm/sup 2/, ionizing 1.17-1.33 MeV Co/sup 60/ dose levels in excess of 200 Mrad(GaAs) and dose rate levels reaching 1.89/spl times/10/sup 11/ rad(GaAs)/s is presented in terms of proper components and parameter choices, DC/RF electrical measurements and test methods under irradiation. Experimental results are explained together with drift analyses of electrical parameters that have determined threshold limits of component degradations. Modelling the effects of radiation on GaAs components relies on degradation analysis of active layer which appears to be the most sensitive factor. MMIC's degradation under neutron fluence was simulated from irradiated FET data. Finally, based on sensitivity of technological parameters, rad-hard design including material, technology and MMIC design enhancement is discussed.

PIN diode and neutron spectrum measurements at the Army Pulse Radiation Facility

Neutron spectrum measurements using the foil activation technique have been made in two widely varying environments. One is an extremely high neutron-to-gamma field and the other extremely low. These measurements were used to characterize the fields and to evaluate the use of the DN-156 PIN diode for measuring 1 MeV equivalent neutron fluence in silicon (/spl Phi/1 MeV(Si)). The agreement between the /spl Phi/1 MeV(Si) as measured with diodes and as determined by the spectral measurements was within /spl plusmn/5%. A proton recoil neutron spectrum measurement was also made in the low gamma environment. >

Modelling the effects of neutron radiation on the Gummel-Poon parameters for bipolar NPN transistors

Silicon NPN transistor types 2N2484, 2N2222, and ECG47 were exposed to 1 MeV equivalent neutron fluence levels of 1E+12 to 1E+14 cm −2. The Gummel-Poon static large-signal model parameters were determined before and after irradiation. The results are used to accurately model irradiated transistors operating at all current levels in the forward active region. An analysis is presented on the change in the Gummel-Poon parameters due to neutron irradiation observed in this work which shows that the Ahlport and Anderson models for the damage factor can be derived from our results and are a consistent subset of our findings.