High frequency positive series resistance in IMPATT devices

Abstract

A generalized computer method, which considers drift, diffusion and tunnel currents has been formulated and used to determine the high frequency series resistance (<i>R</i>_s) and its distribution profile along the active layer of a varieties of Avalanche Transit Time (ATT) diode structures. The method is also capable of providing RF properties of the diodes like RF

negative resistance (Z_R), band width and mean square noise voltage <<i>V</i>²>/d<i>f</i> and other parameters at various frequencies. The result indicates generation of high value of <i>R</i>_s<i>, </i>Z_R and <<i>V</i>²>/d<i>f</i> for lo-hi-lo and hi-lo double drift region (DDR) diodes as compared to flat profile diodes. A comparison of the series resistance (<i>R</i>_s), microwave properties and noise generation of Si, GaAs and InP DDR diodes has also been made in this paper. The <i>R</i>_s distribution profiles for the hi-lo and lo-hi-lo DDRs are observed to have double spike like profile unlike the normal double peak profiles for flat DDRs.