Electron barrier height at CuxTe1 − x/Al2O3 interfaces of conducting bridge memory stacks

We addressed the possible variation of the electron barrier at the Cu0.6Te0.4/Al2O3 interface as compared to the pure Cu electrode case. The experiments were performed using structures fabricated by atomic layer deposition of an Al2O3 insulator on (100)Si or thermally oxidized (100)Si, followed by sputtering of Cu or Cu0.6Te0.4 top electrodes. These structures were used to observe electron photoemission from the metal layer into the oxide in order to determine the energy barrier for electrons between the Fermi level of the metal and the conduction band of the insulating layer. The electron barrier height at interfaces of Cu and Cu0.6Te0.4 electrodes is found to be the same but appears to be sensitive to the oxide type which is ascribed to the formation of a polarization layer.

► Photoemission of electrons from Cu and Cu0.6Te0.4 into Al2O3 and SiO2 is observed.
► The same interface barrier heights are found for Cu and Cu0.6Te0.4 on both oxides.
► The barriers on Al2O3 are about 3.5 eV, i.e., 0.3 eV lower than those on SiO2.
► There is a significant impact of polarization layer on the metal/Al2O3 barriers.