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Reactively sputtered hafnium oxide on silicon dioxide: Structural and electrical properties

: Kolkovsky, V.; Lukat, K.; Kurth, E.; Kunath, C.


Solid-State Electronics 106 (2015), S.63-67
ISSN: 0038-1101
Fraunhofer IPMS ()

The structural and electrical properties of SiO2/HfO2 with different thickness of HfO2 grown by the magnetron sputtering technique are investigated. We show that a part of HfO2 is always amorphous in as-grown layers whereas the polycrystalline phase in the form of conical grains can be also observed in HfO2 with the thickness more than 21 nm. The presence of the conical grains seems to be responsible for the formation of interface states or near-interface oxide defects which influence the electrical properties of the films leading to the shift of the flat-band voltage and to the appearance of the conductance peaks near 0 V. These defects are found to be stable even after the heat treatment at about 950 °C which leads to the crystallization of HfO2 films irrespective of their thickness.