Effects of high-temperature gamma ray and electron irradiation on npn Si transistors

Abstract

The degradation of npn Si transistors, subjected to /spl gamma/ and 1-and 2-MeV electrons at different irradiation temperature, is studied. For the 20/spl deg/C irradiation I/sub B/ increases significantly, while I/sub C/ markedly decreases for V/sub BE/ above 0.6 V. The radiation-induced degradation becomes significantly smaller for higher exposure temperatures. For the 200/spl deg/C irradiation, I/sub B/ remains of the same order as before irradiation, while I/sub C/ is nearly identical. It is also noticed that h/sub FE/ for the 200/spl deg/C /spl gamma/-ray irradiation amounts to 82% of the starting value. A broad distribution of hole trapping levels is observed in the base region for the 20/spl deg/C exposure, while an electron trap with energy level Ec - 0.18 eV and a broad DLTS signal around 150 K was found in the collector region. The hole capture levels in the base are related to radiation damage at the Si-SiO/sub 2/ interface region. It is concluded that the radiation-induced defects in the base and collector regions correlate well with the device degradation of the npn Si transistors.