Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 102: Epitaxy and growth: Metals and semiconductors II

O 102.2: Talk

Friday, March 18, 2011, 11:30–11:45, WIL C307

Stress induced by NiO monolayers on Ag (100) — •Anita Dhaka, Dirk Sander, and Jürgen Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 061120 Halle (Germany)

We performed in-situ stress and medium energy electron diffraction (MEED) measurements simultaneously during the formation of NiO monolayers (ML) on Ag (100).We deposit Ni at 300 K in an O₂ partial pressure of 2×10⁻⁷ mbar [1]. Our stress measurement reveals a compressive stress change of -6.5 N/m after growth of 5 ML NiO.This stress measurement is ascribed to misfit stress, which is calculated as −6.3 N/m for 5 ML. From 5 to 10 ML almost constant stress is observed, and low energy electron diffractin (LEED) shows broadened spots, developing into a streaky diffraction pattern. We conclude that misfit distortions are formed, and pseudomorphic growth ends at 5 ML. MEED oscillations indicate layer-by-layer growth from 2 to 10 ML. The first ML NiO gives a (1×2) LEED pattern [2], and the stress change is +0.48 N/m. We ascribe this to an inhomogeneous surface coverage, which is composed of Ni, NiO and Ag areas, as suggested in STM work [2]. We conclude that combined stress and diffraction measurements identify different growth regimes and film stress in epitaxial oxide monolayers, quantitatively. Financial support by SFB 762 is gratefully acknowledged. [1] K.Marre and H.Neddermeyer, Suf. Sci. 287/288, 995 (1993)

[2] Stephan Groβer, Christian Hagendorf, Henning Neddermeyer and Wolf Widdra, Surf. Interface Anal. 40, 1741-1746 (2008)