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DS: Fachverband Dünne Schichten

DS 49: Atomic Layer Deposition

DS 49.6: Vortrag

Freitag, 4. April 2014, 11:15–11:30, CHE 91

Atomic layer deposition of Sr_xTi_1−xO_y: Stoichiometry variation and layer characterization — •Solveig Rentrop¹, Barbara Abendroth¹, Hartmut Stöcker¹, Ralph Strohmeyer¹, Jura Rensberg², Juliane Walter¹, and Dirk C. Meyer¹ — ¹Institut für Experimentelle Physik, TU Bergakademie Freiberg — ²Institut für Festkörperphysik, Universität Jena

Resistance switching of metal-insulator-metal (MIM) capacitor structures is one of the possible routes for future non-volatile random access memories. A promising ternary dielectric for MIM devices is Sr_xTi_1−xO_y. In this material, the layer composition is found to determine dielectric and optical properties as well as the band gap.

Here, we present studies on the atomic layer deposition of amorphous SrTiO₃ from Sr(iPr₃Cp)₂, Ti[N(CH₃)₂]₄ and H₂O at substrate temperatures of 300 ^∘C and 320 ^∘C, resp. By changing the Sr/Ti pulse ratio, we are able to tailor the stoichiometry from stoichiometric to Sr or Ti excess. The layer composition is obtained from X-ray fluorescence spectroscopy and Rutherford backscattering. The tuned band gap value is determined by using a Tauc plot of the ellipsometric absorption coefficient. Moreover, we investigated the dependencies of optical constants, layer density and surface morphology on the layer composition.

Carbon incorporated during deposition increases the leakage current. By X-ray photoelectron spectroscopy the carbon content was measured after Ar ion cluster sputtering. The results show that we are able to deposit carbon free Sr_xTi_1−xO_y layers for different Sr/Ti ratios.