Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 13: Preparation and characterization

HL 13.2: Talk

Monday, March 11, 2013, 13:00–13:15, H15

Stability of AlOx Gate Dielectrics for High Temperature Field Effect Transistors — •Björn Christian², Volker Cimalla¹, Lutz Kirste¹, Martina Baeumler¹, Frank Bernhardt¹, Fouad Benkhelifa¹, and Oliver Ambacher^{1, 2} — ¹Fraunhofer Institute for Applied Solid State Physics Freiburg, Germany — ²Laboratory for Compound Semiconductor Microsystems, Department of Microsystems Engineering - IMTEK, University of Freiburg, Germany

AlO_x is a promising high-k dielectric material to replace SiO₂ in field effect transistors scaled to smaller dimensions (< 100 nm) or operating at higher temperatures. High temperature operation, however, causes phase transitions such as crystallization of metal oxides, which has a negative impact on the properties of dielectric layers. Dielectric films can be stabilized in nanolaminates using stacks of different dielectric materials. In this work, the phase transitions and their impact on the electrical properties of aluminum oxide as a single layer as well as stacks of aluminum oxide, silicon oxide and differently prepared silicon nitride has been characterized. Basic film properties and crystallization were investigated by x-ray diffraction, spectral ellipsometry, and scanning microscopy techniques. Electrical properties have been analyzed by C/V and I/V measurements. In addition, device structures based on AlGaN/GaN HEMTs were prepared and the influence of the gate stacks on threshold voltage was analyzed.