Application of Pelletron Accelerator to Study Total Dose Radiation

The exposure of metal¿oxide¿semiconductor (MOS) and bipolar devices to the ionizing radiation induces interface and oxide trapped charge in the field oxide, in addition to point defects. These radiations induced trapped charges and defects degrade the electrical characteristics of the devices. In order to use MOS and bipolar devices in space and other radiation rich environments, the devices need to withstand a few krad to 10¿s of Mrad of gamma equivalent total dose. Therefore it is important and interesting to understand different radiation effects on MOS and bipolar devices. The N-channel depletion MOSFETs and silicon NPN transistors were irradiated with heavy ions such as 175 MeV Ni13+ ions, 140 MeV Si10+ ions, 100 MeV F8+ ions, 95 MeV O7+ ions and 48 MeV Li3+ ions in the dose range of 100 krad to 100 Mrad. The ion irradiation results are compared with Co-60 gamma irradiation results in the same total dose levels for both the devices. The I-V characteristics of the MOSFETs and NPN transistors were studied using Agilent semiconductor parameter analyzer 4155C and Keithley dual channel source meter model 2636A.