Seltenerd-basierte ternäre Oxide als alternative Gatedielektrika

Roeckerath, Jens Martin

Dissertation / PhD Thesis/Book

Seltenerd-basierte ternäre Oxide als alternative Gatedielektrika

Roeckerath, J. M. (Corresponding author)FZJ*

2008
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-89336-543-2

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Schriften des Forschungszentrums Jülich. Information / Information 3, 148 S. (2008) = RWTH Aachen, Diss., 2008

Please use a persistent id in citations: http://hdl.handle.net/2128/3601

Abstract: For the further scaling of silicon-based field effect transistors the use of alternative gate dielectrics with $\kappa$>20 – so called high-$\kappa$ dielectrics – is crucial. Only with these materials the leakage currents in the devices can be kept below a critical limit compared to the so far used silicon dioxide. And, the ongoing reduction of feature size of integrated circuits ist the basis for the success of microelectronics industry during the last four decades. Thermodynamic calculations predict that some rare earth based ternary oxides (e.g. $\textit{RE}$ScO$_{3}$ or $\textit{RERE}$O$_{3}$ with $\textit{RE}$ = Y, La or an element from the lanthanide group) are stable in contact with silicon and therefore being considered for the use as alternative gate dielectrics. In this work, GdScO$_{3}$ and LaLuO$_{3}$ thin films deposited with different techniques (pulsed laser deposition, atomic layer deposition and electron beam evaporation) were morphologically and electrically characterized. The produced films are stoichiometric, homogeneous and smooth. They reveal dielectric constants as high as 23 for GdScO$_{3}$ and even up to 32 for LaLuO$_{3}$, undisturbed C-V curves and low leakage current densities. Furthermore, a process for the integration of GdScO$_{3}$ as gate dielectric into silicon-based field effect transistors was developed. The prepared devices show normal transfer and output characteristics. Carrier mobilities of about 120 cm$^{2}$/Vs for bulk silicon and 155 cm$^{2}$/Vs for silicon on insulator substrates were determined. The use of strained silicon yields an improvement of 140% for the carrier mobility and about 30% for the maximum drain current and a doubling of the maximum transconductance. The integration of GdScO$_{3}$ as gate dielectric into AlGaN/GaN-MISHFETs resulted in a reduction of the gate leakage current by four orders of magnitude, a doubling of the output power, and a significant improvement of the power added efficiency. In summary, the results of this work confirm the suitability of the rare earth based ternary oxides GdScO$_{3}$ and LaLuO$_{3}$ for the use as alternative gate dielectrics in microelectronics.

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