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Tunnel junctions of Co͑10 nm͒/AlO x ͑nominally 2 nm͒/Co͑20 nm͒ have been prepared by molecular beam epitaxy applying a shadow mask technique in conjunction with an UV light-assisted oxidation process of the AlO x barrier. The quality of the AlO x barrier has been proven by x-ray photoelectron spectroscopy and temperature dependent tunneling magnetoresistance ͑TMR͒ measurements. Optimum-oxidized tunnel junctions show a TMR of 20% at 285 K and up to 36% at 100 K. At 285 K the TMR values as a function of oxidation time are not symmetric about the optimum time. For underoxidized junctions the TMR is reduced more strongly than for overoxidized junctions. The temperature dependence of the junction's resistance is a clear and reliable indicator whether pinholes ͑or imperfections͒ contribute to the conduction across the barrier.Magnetic tunnel junctions ͑MTJs͒ consisting of two ferromagnetic electrodes separated by a thin insulating layer ͑typical AlO x ͒ show large tunnel magnetoresistance ͑TMR͒ at room temperature making them promising candidates for magnetic random access memory ͑MRAM͒ devices.

The major issue of RRAM is the uneven sneak path that limits the array size. For the first time record large One-Resistor (1R) RRAM array of 128x128 is realized, and the array cells at the worst case still have good Low-/High-Resistive State (LRS/HRS) current difference of 378 nA/16 nA, even without using the selector device. This array has extremely low read current of 9.7 μA due to both low-current RRAM device and circuit interaction, where a novel and simple scheme of a reference point by half selected cell and a differential amplifier (DA) were implemented in the circuit design.

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