STUDY OF RADIATION (NEUTRON, γ-RAY, AND CARBON-IRON) EFFECTS ON NPN BIPOLAR TRANSISTORS
Integrated microscopic investigations of bipolar junction damages in silicon detectors following neutron irradiation and studies of the degradation of the performance of bipolar transistors, due to generation of defects in silicon irradiated with neutron and ion carbons, were performed. The integrated microscopic investigations were studied by means of an advanced contact potential difference (CPD) method in atomic force microscopy (AFM). It was shown that gain degradation appears and that the density of generated defects is the same for neutron and carbon irradiation, but the density of created Frenkel pairs (interstitial-vacancy) is smaller for neutrons than for carbon ions. The value of Δ(1/β) of the transistor was evaluated from the density of Frenkel pairs (CF), for given value of Φ. The dependence of Δ(1/β) on concentration of CF for lateral and vertical pnp juntions at Ic=1μm, was shown. Fron the data of density of Frenkel pairs as a function of ratio Φ (R), was obtained, R=CF/Φ. Ratio R was independent on Φ, for a given type of irradiation (neutrons or carbon ions). For carbon ions, R depends on the value of the energy of incident particles (medium energy 11.1 MeV/a and high energy 95.0 MeV/a of the carbon ions.
