Regensburg 2016 – scientific programme

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DS: Fachverband Dünne Schichten

DS 3: Phase Change / Resistive Switching

DS 3.6: Talk

Monday, March 7, 2016, 10:45–11:00, H8

Resistive switching in oxygen engineered TaO_x and Ta:HfO_x based RRAM devices grown by MBE — •Merin Jissy Joseph¹, S.U. Sharath¹, Stefan Vogel¹, Erwin Hildebrandt¹, Philipp Komissinskiy¹, Thomas Schroeder², and Lambert Alff¹ — ¹Institute of Materials Science, Technische Universität Darmstadt, Germany — ²IHP, Frankfurt (Oder), Germany

With conventional flash based non-volatile memories (NVM) gradually approaching its limitations of scaling, resistive random access memory (RRAM) based on CMOS compatible metal oxides (HfO_x, TaO_x etc.) is among the widely investigated choices of next generation NVM. Techniques like oxygen engineering [1] and doping is of interest in reducing the forming voltage and improving the effective device yield in HfO_x based RRAM devices. Resistive switching characteristics were investigated in TaO_x and Ta:HfO_x thin films grown on titanium nitride (TiN) electrodes by reactive molecular beam epitaxy (MBE). TaO_x based devices show a strong dependence of the forming voltage on oxidation conditions. A comparison of amorphous and polycrystalline Ta:HfO_x based devices showed tunable and opposite forming voltage trends with changing composition and doping, highlighting the role of grain-boundaries. One important result is that Ta doping increases the stability of the resistive states, irrespective of crystallinity. Under fixed oxidation conditions, Ta doping in HfO_x was found to reduce the forming voltage while at the same time the resistance ratio is even increased to above ten thousand (10.000).
S. U. Sharath et al., Appl. Phys. Lett. 104, 063502 (2014).