The effects of impact ionization on the operation of neighboring devices and circuits

This paper examines the detrimental effects of excess majority carriers and photons induced by impact ionization on the operation of neighboring pn junctions, bipolar transistors, MOS transistors, and circuits. The experimental results show that in addition to an increase in the substrate surface potential due to the excess majority carriers, photons can lower the barrier of a pn junction and, as a consequence, shift the Gummel plot of an npn bipolar transistor. As for the neighboring circuits, an example in which the speed of an NMOS ring oscillator is retarded by impact ionization in a neighboring NMOS transistor is presented.>