Influence of metal electrode stoichiometry on the electron barrier height at CuxTe1−x/Al2O3 interfaces for CBRAM applications

• Photoemission of electrons from CuxTe1−x and Te into Al2O3 and SiO2 is observed.
• The CuxTe1−x stoichiometry has a marginal impact on the electron barrier height.
• Application of Te electrodes leads to the increase of the barrier height.
• EWF of Cu and Te on Al2O3 are considerably higher than vacuum WF.
• Negative charges may be present at the CuxTe1−x/Al2O3 interface.

Spectroscopy of Internal photoemission of electrons was applied to reveal the impact of the stoichiometry of CuxTe1−x (0 ⩽ x ⩽ 1) electrodes on the barrier height between the electrode Fermi level and the bottom of the Al2O3 conduction band. The barriers observed in the structures with atomic layer deposited alumina films (20 or 10 nm) on (1 0 0) Si substrates are compared to the metal/SiO2 barriers in capacitors with thermally grown Si oxide. We found that the CuxTe1−x stoichiometry has a marginal impact on the barrier height, yielding the same value for the Cu metal electrode even for high Te concentration (80%). In the case of pure Te electrode the photoemission spectral threshold is found to be shifted towards higher photon energy by 0.5 eV.

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