I-V and DLTS study of generation and annihilation of deep-level defects in an oxygen-ion irradiated bipolar junction transistor

Abstract

A commercial bipolar junction transistor (2N 2219A, npn) irradiated with 84 MeV O6+-ions with fluence of the order of 1013 ions cm−2 is studied for radiation-induced gain degradation and deep-level defects or recombination centers. I-V measurements are made to study the gain degradation as a function of ion fluence. Properties such as activation energy, trap concentration and capture cross section of deep levels are studied by deep-level transient spectroscopy. Minority carrier trap energy levels with energies ranging from E C −0.17 eV to E C −0.55 eV are observed in the base–collector junction of the transistor. Majority carrier defect levels are also observed with energies ranging from E V +0.26 eV to E V +0.44 eV. The irradiated device is subjected to isothermal and isochronal annealing. The defects are seen to anneal above 250 °C. The defects generated in the base region of the transistor by displacement damage appear to be responsible for an increase in base current through Shockley-Read-Hall or multi-phonon recombination and consequent transistor gain degradation.