Impact ionization at very low voltages in silicon

Publisher Website
Google Scholar
Abstract
Impact ionization in germanium and silicon has been the subject of extensive theoretical and experimental work. The general agreement in the literature for the value of the threshold energy for impact ionization is 1.5 times the energy gap (EG) at room temperature which corresponds to 1.65 eV in the case of silicon. In this work, using a metal semiconductor field effect transistor (MOS device), as a sensitive tool for detecting small multiplication currents, impact ionization is investigated in a region where the total potential drop over which carriers are accelerated is less than the threshold energy for impact ionization. Impact ionization currents are detected for potential drop as low as 1.1 V. The positive temperature coefficient in this region suggests that the initial thermal distribution of the electrons dominates impact ionization for very low accelerating voltages.