Nonpolar resistive memory switching with all four possible resistive switching modes in amorphous ternary rare earth LaHoO3 thin films

We studied the resistive memory switching in pulsed laser deposited amorphous LaHoO3 (LHO) thin films for non-volatile resistive random access memory (RRAM) applications. Nonpolar resistive switching (RS) was achieved in PtLHOPt memory cells with all four possible RS modes ( positive unipolar, positive bipolar, negative unipolar, and negative bipolar) having high RON and ROFF ratios (in the range of 104 to 105) and non-overlapping switching voltages (set voltage, VON 3.6 to 4.2 V and reset voltage, VOFF 1.3 to 1.6 V) with a small variation of about 5 to 8 percent. X ray photoelectron spectroscopic studies together with temperature dependent switching characteristics revealed the formation of metallic holmium (Ho) and oxygen vacancies (VO) constituted conductive nanofilaments (CNFs) in the low resistance state (LRS). Detailed analysis of current versus voltage characteristics further corroborated the formation of CNFs based on metal like (Ohmic) conduction in LRS. Simmons Schottky emission was found to be the dominant charge transport mechanism in the high resistance state.