TY  - JOUR
AU  - Kubacki, Jerzy
AU  - Molak, Andrzej
AU  - Rogala, Maciej
AU  - Rodenbücher, Christian
AU  - Szot, Krzysztof
TI  - Metal–insulator transition induced by non-stoichiometry of surface layer and molecular reactions on single crystal KTaO$_{3}$
JO  - Surface science
VL  - 606
IS  - 15-16
SN  - 0039-6028
CY  - Amsterdam
PB  - Elsevier
M1  - FZJ-2015-04185
SP  - 1252 - 1262
PY  - 2012
AB  - In the study we present results on topography, morphology, chemical composition, electronic structure and electrical properties of the (100) surface layer of KTaO3 single crystal caused by sputtering with Ar+ ion beam with energy of 1 keV. Several surface sensitive techniques, i.e. X-ray photoelectron spectroscopy (XPS), local conductivity of atomic force microscopy (LC-AFM), and Kelvin Probe Force Microscopy (KPFM) were used. The observed changes in the electronic structure were explained as a result of the chemical decomposition of the surface layer. A correlation between the electronic states which appeared in the energy gap and the changes in charge state of Ta ions was found. The activation energy related to averaged local conductivity temperature dependence was estimated from Arrhenius plot. It was also found, that variations in the local contact potential difference (LCPD) indicated changes in the chemical composition in nano-scale. The chemical reconstruction of the KTaO3 surface modified by Ar+ ion beam was deduced. This non-homogeneity corresponded to 2-D non-homogeneity of the local electric conduction (LC-AFM), which occurred within nano-areas after sputtering. Chemical reactivity of the modified surface with CO2 and O2 was observed. The reversibility of the Ar+ induced loss of oxygen non-stoichiometry was observed after the sample was exposed to various doses of O2. The successful reversibility occurred after oxidation process at high temperature, i.e. 300 °C.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000305845600023
DO  - DOI:10.1016/j.susc.2012.04.005
UR  - https://juser.fz-juelich.de/record/201895
ER  -