Details

Autor(en) / Beteiligte

• Celinska, Jolanta
• McWilliams, Christopher
• Paz de Araujo, Carlos
• Xue, Kan-Hao

Titel

Material and process optimization of correlated electron random access memories

Ist Teil von

• Journal of applied physics, 2011-05, Vol.109 (9), p.091603-091603-7

Ort / Verlag

American Institute of Physics

Erscheinungsjahr

2011

Link zum Volltext

Quelle

AIP Journals Complete

Beschreibungen/Notizen

• A method of making transition metal oxide materials that result in resistive switching properties stable over time and temperature is described. We have developed an ultra low temperature (≤450°C) process for carbonyl ligand modified NiO thin films based on the chemical solution deposition (CSD) for correlated electron random access memory (CeRAM) applications. CeRAMs form the general class of devices that use the electron-electron interaction as the primary mode of operation. These devices are fabricated in the conductive state (born-ON), thus, they do not require electroforming to enter the variable resistance state. Several process parameters such as film stoichiometry, thickness, annealing temperature and ambient have been investigated to optimize CeRAMs properties. We present the coordination number 'fine tuning' in NiO ultra thin films via carbonyl ligand doping that regulate the number of oxygen vacancies and the surface excess of metal ions. CeRAMs contrary to just standard NiO based resistive memories use the pure Mott-like charge transfer insulator in which an abrupt metal to insulator transition is the dominant mechanism without the aid of charge trapping vacancies. In our films the effect of the oxygen vacancies are canceled due to the stabilizing effect of the carbonyl based extrinsic ligand. In this paper, detailed process sequence and the extrinsic ligand doping scheme is described in some length. It is shown that complexes formed by the introduction of the extrinsic ligand promote Ni 2+ ions to enter the disproportionation reaction Ni 2+ +Ni 2+ →Ni 1+ +Ni 3+ which is considered to be responsible for the memory mechanism.