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In this letter, we explore the influence of the CuxTe1-x layer composition (0.2 < x < 0.8) on the resistive switching of CuxTe1−x/Al2O3/Si cells. While x > 0.7 leads to large reset power, similar to pure-Cu electrodes, x < 0.3 results in volatile forming properties. The intermediate range 0.5 < x < 0.7 shows optimum memory properties, featuring improved control of filament programming using <5 μA as well as state stability at 85 °C. The composition-dependent programming control and filament stability are closely associated with the phases in the CuxTe1−x layer and are explained as related to the chemical affinity between Cu and Te.

Vanadium dioxide (VO 2 ) has the interesting feature that it undergoes a reversible semiconductor-metal transition (SMT) when the temperature is varied near its transition temperature at 68°C. 1 The variation in optical constants makes VO 2 useful as a coating material for e.g. thermochromic windows, 2 while the associated change in resistivity could be interesting for applications in microelectronics, e.g. for resistive switches and memories. Due to aggressive scaling and increasing integration complexity, atomic layer deposition (ALD) is gaining importance for depositing oxides in microelectronics. However, attempts to deposit VO 2 by ALD result in most cases in the undesirable V 2 O 5 .In the present work, we demonstrate the growth of VO 2 by using Tetrakis[EthylMethylAmino]Vanadium and ozone in an ALD process at only 150°C. XPS reveals a 4+ oxidation state for the vanadium, related to VO 2 . Films deposited on SiO 2 are amorphous, but during a thermal treatment in inert gas at 450°C VO 2 (R) is formed as the first and only crystalline phase. The semiconductor-metal transition has been observed both with in-situ X-ray diffraction and resistivity measurements. Near a temperature of 67°C, the crystal structure changes from VO 2 (M1) below the transition temperature to VO 2 (R) above with a hysteresis of 12°C. Correlated to this phase change, the resistivity varies over more than 2 orders of magnitude. This work has been accepted for publication in Applied Physics Letters. The inset shows the in-situ XRD measurement from which the peak intensity was integrated.

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