9-STATE RESONANT TUNNELING DIODE MEMORY

We demonstrate an epitaxial series combination of eight pseudomorphic AlAs/In0.53Ga0.47As/InAs resonant tunneling diodes (RTD's) grown by molecular beam epitaxy on InP. This series RTD produces an eight-peak multiple negative differential resistance characteristic with a peak-to-valley current ratio (PVR) exceeding 2 per peak at a peak current density of approximately 6 kA/cm2. Hysteresis in the current-voltage characteristic is reduced by uniformly Si doping the double-barrier resonant tunneling region at a density of 5 x 10(16) cm-3. Using this multiple-peak RTD in series with a field-effect transistor load, a nine-state multivalued memory circuit is demonstrated.