Inkjet-printed ReRAM is flexible

April 18, 2017 //By Peter Clarke
A research team from the University of Applied Sciences Munich has reported resistive non-volatile memory cells (ReRAM) on flexible substrates made entirely by ink-jet printing.

The cells feature switching voltages at 0.5V, low write currents, and a high ratio between high and low resistance state of 10^4. The high ratio also allows distinguishing of up to eight state of Ron and therefore 3bit multibit storage in a single memory cell.

The cell consists of a silver top electrode over silicon-dioxide-based spin-on-glass insulation layer over PEDOT-PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) bottom layer on a 125-micron thick PEN foil (Teonex Q65HA from Dupont Teijin Film).

The nano-porous spin-on-glass acts as an insulator and as a matrix for ion migration and growth of a metallic filament in the manner of a conductive-bridging RAM (CBRAM). The memory cell was approximately 100-micron by 100-micron cross-point. To avoid dealing with array addressing issues the memories were composed multiple cells on a single word line.

A standard FujiDimatix DMP 2831 inkjet printer was used for the printing of all 3 layers of our memory cells.

In an un-flexed state at a voltage of approximately 0.5 V, the cells switch from the high resistance off-state to the low resistance on-state and return back to off at −0.05 V. The low switching voltages combined with the small write currents, due to the high resistance of the underlying PEDOT polymer electrodes enable low power consumption memory devices. No electroforming was required as the switching mechanism is via defects in the SOG, the researchers said.

The cells feature low switching voltages, low write currents, and a high ratio between high and low resistance state of 10^4. Combined with excellent switching characteristics under bending conditions, these results pave the way for low-power and low-cost memory devices for future applications in flexible electronics.

Next: Testing under bending