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DS: Fachverband Dünne Schichten

DS 38: Phase change/ resistive switching

DS 38.9: Vortrag

Donnerstag, 19. März 2015, 17:15–17:30, H 0111

Effect of oxygen engineering and doping on resistive switching in HfO₂ based RRAM devices grown by MBE — •S.U. Sharath¹, Jose Kurian¹, Erwin Hildebrandt¹, Philipp Komissinskiy¹, Thomas Bertaud², Christian Walczyk², Pauline Calka², Thomas Schroeder², and Lambert Alff¹ — ¹Materialwissenschaft, Technische Universität Darmstadt, Germany — ²IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany

Thin films of titanium nitride (TiN, electrode) and hafnium oxide (HfO₂) were grown using molecular beam epitaxy (MBE). Oxygen engineering using strongly oxygen deficient growth parameters and trivalent doping of HfO₂ thin films has been utilized to stabilize oxygen vacancy concentrations far beyond the thermodynamical equilibrium. Thin films of hafnium oxide grown at 320  ^∘C on TiN crystallize in a monoclinic symmetry (m-HfO₂) at higher oxidation conditions, whereas the oxygen deficient hafnium oxide films showed oxygen vacancy stabilized tetragonal like phase of hafnium oxide (t-HfO_2−x) which was verified by X-ray diffraction [1]. A large concentration of oxygen vacancies lead to a defect band at the Fermi-level as observed by X-ray photoelectron spectroscopy (XPS). The electrical switching measurements show that the forming voltage is reduced for oxygen deficient films paving the way for low power devices in future. In oxygen deficient HfO_2−x thin films grown on TiN/Si(001), the thickness dependence of the forming voltage is strongly suppressed [2].

[1] S. U. Sharath et al., Appl. Phys. Lett., 104, 063502 (2014).

[2] S. U. Sharath et al., Appl. Phys. Lett., 105, 073505 (2014).