Dresden 2014 – scientific programme
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DS: Fachverband Dünne Schichten
DS 12: High- and low-k-dielectrics (Joint Session with DF)
DS 12.3: Talk
Tuesday, April 1, 2014, 11:10–11:30, GER 37
Comparison of different gate dielectrics for GaN based high electron mobility transistors — •Annett Freese1, Stefan Schmult2, Andre Wachowiak1, and Thomas Mikolajick1,2 — 1NaMLab gGmbH, Nöthnitzer Str. 64, D-01187 Dresden — 2TU Dresden, Institute of Semiconductor and Microsystems (IHM), Nöthnitzer Str. 64, D-01187 Dresden
The wide-bandgap and high electron mobility make gallium nitride (GaN) based heterostructures particularly interesting for future high-power switching applications. However, conventional GaN heterostructure field effect transistors (HFET) use a simple Schottky gate contact. Thus, they suffer from undesired high gate leakage currents and current collapse. To eliminate these challenges, a dielectric material can be placed between the gate electrode and the semiconductor. Aluminium oxide (Al2O3), hafnium oxide (HfO2), and zirconium dioxide (ZrO2) are potential candidates for such a gate dielectric material due to their high dielectric constant as well as their high conduction band offset to GaN. Learning from silicon processing technology, a successful integration of a suitable dielectric does not only depend on its material properties, but also relies heavily on the nature of the interfaces to the top and bottom electrodes. In this work we investigated Al2O3, HfO2 and ZrO2 with respects to their structural and electrical properties on GaN. The influence of the deposition methods, Molecular Beam Deposition (MBD) and Atomic Layer Deposition (ALD), on the film quality was studied.