Self-consistent transit-time model for a resonant tunnel diode

We present a self-consistent compact model for the small-signal impedance of a resonant tunnel diode (RTD) with a finite collector transit time. The effect of the collector transit time on the device impedance is described for three In/sub 0.53/Ga/sub 0.47/AsAlAs-InAs RTDs with current densities ranging from 14 kA/cm/sup 2/ to 570 kA/cm/sup 2/ with various collector spacer lengths for dc biasing in both the positive and negative differential resistance regions.