A multiple-state memory cell based on the resonant tunneling diode

The device consists primarily of several molecular-beam-epitaxy (MBE-) grown GaAs/(AlGa)As resonant tunneling diodes connected in parallel. This device exhibits multiple peaks in the I-V characteristic. When a load resistor is connected, the circuit can be operated in a multiple stable mode. With this concept, implementation of three-state and four-state memory cells are made. In the three-state case the operating points at voltages V/sub 0/=0.27 V, V/sub 1/=0.42 V, and V/sub 2/=0.53 V represent the logic levels 0, 1, and 2. Similarly for the four-state memory cell the logic levels voltages are V/sub 0/=0.35 V, V/sub 1/=0.42 V, V/sub 2/=0.54 V, and V/sub 3/=0.59 V. A suggestion of an integrated device structure using this concept is also presented.< >