Dresden 2017 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 48: Oxide Semiconductors (jointly with HL)
DS 48.9: Vortrag
Freitag, 24. März 2017, 12:15–12:30, POT 51
Ozone, oxygen and water interaction with In2O3(111) surfaces — •Theresa Berthold1, Stefan Krischok1, Marcel Himmerlich1, Vladimir Polyakov2, Volker Cimalla2, Julius Rombach3, and Oliver Bierwagen3 — 1Institut für Mikro- und Nanotechnologien MacroNano, Technische Universität Ilmenau — 2Fraunhofer-Institut für Angewandte Festkörperphysik, Freiburg — 3Paul-Drude-Institut für Festkörperelektronik, Berlin
In2O3 films are widely used in conductometric gas sensors based on their surface electron accumulation layer (SEAL) whose conductance is influenced by gas adsorption [1]. In this study the chemical composition and electronic surface properties of undoped and Mg-doped In2O3(111) films grown by plasma-assisted molecular beam epitaxy are analyzed by photoelectron spectroscopy. We analyze the formation or desorption (by UHV annealing or UV illumination) of adsorbates, the generation of defects as well as the variation in surface band bending, electron concentration, and surface dipole. Towards understanding the gas sensitivity under realistic conditions we study the effect of humidity on the sensor properties by experiments combining water interaction with ozone or oxygen surface oxidation. H2O partially reverses the depletion/reduction of the SEAL after surface oxidation. Complete depletion of the SEAL is found after plasma oxidation [2]. The experimental results are combined with Schrödinger-Poisson calculations to establish a quantitative analysis of the electron density profile and the density of surface states. [1] J. Rombach et al., Sens. Actuators B, 236, 909 (2016) [2] T. Berthold et al., J. Appl. Phys. (submitted)