Electrochemical Synthesis and Nonvolatile Resistance Switching of Mn3O4 Thin Films
An electrodeposition method is introduced to produce crystalline films of Mn3O4 from aqueous solution. the films are electrodeposited potentiostatically from a solution of 0.2 M Mn(II) acetate at a pH of 6 and a deposition temperature of 80 °C. the anodic deposition is performed in the potential range of 0.275-0.350 V vs. Ag/AgCl/KCl(sat.). in this potential range the current efficiency is 100%. Both the stoichiometry and the morphology of the films can be controlled through the applied potential. Films deposited at a low overpotential grow with a  preferred orientation, columnar microstructure, and near-stoichiometric Mn(III)/Mn(II) ratio of 1.99. Films deposited at higher overpotential deposit with a near-random orientation, porous or powdery microstructure, and Mn(III)/Mn(II) ratio of 2.62. at potentials greater than 0.38 V, amorphous films of MnO2 are produced. the as-deposited Mn3O4 has a very high resistivity of 4.4 × 108 Ωcm. the electrodeposited Mn3O 4 films undergo unipolar, nonvolatile resistance switching. an Au/Mn3O4/AuPd cell can be reversibly switched between a high resistance state (30 MΩ) and a low resistance state (14.8 Ω) by applying SET and RESET voltages of the same polarity. SET and RESET times of approximately 2 and 50 ns were observed. Because of the large resistance contrast between the two states and the persistence of each state, Mn 3O4 is a candidate for future resistive random access memory (RRAM) devices.
J. A. Koza et al., "Electrochemical Synthesis and Nonvolatile Resistance Switching of Mn3O4 Thin Films," Chemistry of Materials, vol. 26, no. 15, pp. 4425-4432, American Chemical Society (ACS), Jan 2014.
The definitive version is available at https://doi.org/10.1021/cm5014027
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