Dresden 2014 – scientific programme

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DS: Fachverband Dünne Schichten

DS 43: Poster II: Organic thin films; Atomic layer deposition, Thin film characterization: Structure analysis and composition (XRD, TEM, XPS, SIMS, RBS, ...)

DS 43.25: Poster

Thursday, April 3, 2014, 16:00–19:00, P1

High quality TiN as bottom electrode for zinc ferrite based magnetic tunnel junctions grown by pulsed laser deposition — •Michael Bonholzer, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig

A highly conductive interlayer is required for a successful device implementation of spinel oxides in magnetic tunnel junctions (MTJs) [1]. We use zinc ferrite (ZnFe₂O₄) as ferromagnetic electrodes. To reduce the series resistance of these devices we add a highly conductive titanium nitride (TiN) layer between the magnesium oxide (MgO) substrate and the ZnFe₂O₄ layer. We have achieved to grow atomically smooth hetero-epitaxial TiN thin films on (001) MgO single crystals by pulsed laser deposition (PLD).
In order to generate perfect conditions for two-dimensional growth of TiN on MgO, the substrates are annealed at 950^∘C for 2h in vacuum using a CO₂ laser heater. The annealed substrates show smooth and uniformly stepped surfaces. The terrace height is half a unit cell of MgO; a value of 0.21 nm was measured by atomic force microscopy (AFM). On these substrates we grew TiN thin films by pulsed laser deposition (PLD). In situ RHEED oscillations indicate two dimensional growth mode up to a film thickness of about 50 nm. This is confirmed by AFM measurements; the TiN films show smooth, stepped surfaces with a uniform terrace height of about 0.21 nm. The existence of intensity fringes in the X-ray pattern indicates a high film quality, as well.
[1] M.Opel et al., Phys. Status Solidi A 208, 232 (2011)