Anodized Aluminum Oxide Thin Films for Room‐Temperature‐Processed, Flexible, Low‐Voltage Organic Non‐Volatile Memory Elements with Excellent Charge Retention

Abstract

Despite considerable achievements in organic electronics, including examples of complex integrated circuits, [ 1 ] transistor matrix arrays for optical [ 2 ] and Braille displays, [ 3 ] image scanners, [ 4 ] and large-area electronic skin, [ 5 ] non-volatile organic memories remain underexploited. [ 6 ] Even at the lower end of the market, where potential applications are smart cards, wireless tags, and large-area sensors, no non-volatile memory that meets the minimum requirements in terms of access time, retention, and endurance is currently available. [ 6a ] Although there are several types of memory, such as electret, [ 7 ] ferroelectric polymer, [ 8 ] resistive, [ 9 ] and fl ash, [ 10 ] that may be considered suitable, none of them have reached maturity. Electret memories usually require high operating voltages and suffer from long programming times and low charge retention. [ 7 ] Ferroelectric polymer memories face problems known from their inorganic counterparts: interface charge trapping, fatigue, and imprint. [ 8 ] Resistive memories require currents to operate the memory. [ 9 ] Organic fl ash memories, based on fi eld-effect transistors with a fl oating gate architecture where charges stored in the fl oating gate change the threshold voltage of the transistor, currently suffer from either high voltage operation or low charge retention, typically on the order of a few hours or days. [ 10 ] In fl ash memories, the dielectric used to isolate the fl oating gate from the gate electrode and from the semiconductor is the main problem. The gate dielectric must be dense to achieve extremely low leakage currents, and it must provide very large dielectric breakdown strength. [ 11 ]