Beyond CMOS and RF devices, integrated circuits and technologies

Resistive switching in ferroelectric, polycrystalline YMnO3 thin films

Fig. 1: Current density–voltage (J-V) characteristics of a unipolar resistive switching device with an Al/Y0,94Mn1,05Ti0,01O3/Pt MIM with a current compliance (CC) limit of 5 mA at room temperature. Current density and voltage are plotted on a logarithmic and linear scale, respectively.
© Fraunhofer ENAS
Fig. 1: Current density–voltage (J-V) characteristics of a unipolar resistive switching device with an Al/Y0,94Mn1,05Ti0,01O3/Pt MIM with a current compliance (CC) limit of 5 mA at room temperature. Current density and voltage are plotted on a logarithmic and linear scale, respectively.
Fig. 2: Constant read-out current density of the digital memristors  A (Y1Mn1O3), B (Y0,95Mn1,05O3), C (Y1Mn0,99Ti0,01O3) and D (Y0,94Mn1,05Ti0,01O3) measured with read-out voltage of Ur = +0.1 V at room temperature on Al top electrode of 300 μm diameter.
© Fraunhofer ENAS
Fig. 2: Constant read-out current density of the digital memristors A (Y1Mn1O3), B (Y0,95Mn1,05O3), C (Y1Mn0,99Ti0,01O3) and D (Y0,94Mn1,05Ti0,01O3) measured with read-out voltage of Ur = +0.1 V at room temperature on Al top electrode of 300 μm diameter.

Memristors are passive circuit elements for data processing and non-volatile data processing. The resistance of these passive components is small in the ON state and high in the OFF state. The resistance values can be continuously changed in analog memristors and can be digitally changed in digital memristors. The digital memristors are comparable to other bistable systems, for example to transistors which can be switched between high-resistance (HRS) and low-resistance states (LRS). At Fraunhofer ENAS, we are investigating analog memristors (BiFeO3, BFO) and digital memristors (YMnO3, YMO), since both classes of memristors are required for different purposes, both individually and in combination. The differences in the resistance values of the digital YMO memristor in the HRS and LRS differ by 4–5 orders of magnitude. This makes YMO particularly suitable as a so-called selector material in crossbar structures. Typically, transistors are used as selector materials in cross-bar structures to suppress leakage currents in not directly addressed cells of crossbar structures. The perfectly stoichiometric digital YMO memristor already has very good properties in terms of electroforming-free, endurance, and retention. We examined and optimized the data storage and reading capability of the digital YMO memristor in dependence on the chemical composition of the YMO.