May 25 2007
Micromem Technologies Inc. announced that it has achieved success in tests of radiation hardness on its device components. Samples prepared by Dr. Harry Ruda at the University of Toronto were exposed to various levels of Cobalt 60 gamma radiation. This form of radiation is one of the toughest forms and even after exposure at the highest levels of radiation the materials performed perfectly.
Samples of pHEMT (High Electron Mobility Transistor structures) GaAs were prepared to mimic the bit cell environment of the company’s Hall Sensing MRAM. The samples were then sent for exposure to Cobalt 60 gamma radiation in an industrial medical device sterilization chamber. The samples were exposed to three different doses of radiation as follows (each dose is reported within +/- 5 kGy):
- Low level: Min. 26.371 kGy to max. 31.603 kGy
- Mid level: Min. 45.163 kGy to Max. 52.005 kGy
- High level: Min. 95.139 kGy to Max. 112.747 kGy
Researchers at the University of Toronto then tested the samples. The test concluded the device’s functioning and capabilities remained unaltered by even the highest level of radiation exposure. These initial results were taken at room temperature. The only effects of the radiation exposure that could be seen were at temperatures below -70ºC.
During actual use the device would not be exposed to such extreme temperatures.
The measurements showed that the samples made highly sensitive Hall sensors and were able to function as a memory element after dosing with high levels of radiation.
The next steps have already begun which include making and testing fully integrated bit cells fabricated at the University of Toronto. The company plans to move forward with its testing by fabricating scaled samples inside a fabrication facility. These scaled prototypes will be tested for use as radiation hardened memo ry components for sale into the medical device industry, as well as aerospace, defense and pharmaceuticals.mpetitively on a global basis.”