ULTRARAM: Toward the Development of a III-V Semiconductor, Nonvolatile, Random Access Memory

ULTRARAM is a III-V compound semiconductor memory concept that exploits quantum resonant tunneling to achievenonvolatility at extremely lowswitching energy per unit area. Prototype devices are fabricated in a 2 x 2 memory array formation on GaAs substrates. The devices show 0/1 state contrast from program/erase (P/E) cycles with 2.5 V pulses of 500-mu s duration, a remarkable switching speed for a 20 mu m gate length. Memory retention is tested for 8 x 104 s, whereby the 0/1 states show adequate contrast throughout, whilst performing 8 x 10(4) readout operations. Further reliability is demonstrated via program-read-erase-read endurance cycling for 10(6) cycles with 0/1 contrast. A half-voltage array architectureproposed in our previous work is experimentally realized, with an outstandingly small disturb rate over 10(5) half-voltage cycles.