I-V and deep level transient spectroscopy studies on 60 MeV oxygen ion irradiated NPN transistors

NPN transistors have been irradiated by 60 MeV oxygen ions in a fluence ranging from 5 x 10(10) to 1 x 10(13) ions/cm(2). The DC current gain (h(FE)), excess base current (DeltaI(B) = I-B post - I-B pre), excess collector current (DeltaI(C) = I-C post - I-C pre) and collector saturation current (I-CSat) of the ion irradiated transistors were studied systematically. The hFE of the transistors were found to be decreased drastically after ion irradiation. A significant increase has been observed in the collector current (I-C) along with the increase in the base current (I-B) after ion irradiation. The I-CSat of the ion irradiated transistors were also decreased significantly after irradiation. The radiation induced trap levels in the collector base depletion region of NPN transistors were studied by deep level transient spectroscopy technique and different types of trap levels were observed. The results obtained on the activation energy, density of trap levels, apparent capture cross section, introduction rate and space charge layer lifetime of different defects for different total fluence are presented and discussed. (C) 2003 Elsevier B.V. All rights reserved.