Stacked PIN diode structures for microwave switching

A diode structure consisting of several stacked PIN diodes with tunnel junc tions serving as quasi-Ohmic intercontacts is proposed. This structure is p referable if a microwave switch is required to have both high breakdown vol tage and very small switching time. In this case a conventional (single-bas e) PIN switch has too large forward voltage drop across the base at suffici ently high current densities, because the base length is much greater than the bipolar diffusion length. This leads to high electric fields in the bas e and the development of unwelcome hot-electron effects. The replacement of the long base with several narrow bases connected in series by heavily dop ed p(+)n(+) tunnel inserts solves this problem effectively. Direct numerica l calculations have shown that this slacked structure exhibits a substantia lly smaller DC forward voltage drop at the same switching times (or substan tially smaller switching times at the same DC forward voltage drops). At th e microwave frequency range, the resistance of the stacked structure can be decreased drastically because all the newly formed pn-junctions are shorte d by their large capacitances. (C) 1999 Elsevier Science Ltd. All rights re served.