Polarization-Engineered n+GaN/InGaN/AlGaN/GaN Normally-Off MOS HEMTs
D. Gregušová1, M. Blaho1, Š. Hašcík1, P. Šichman1, A. Laurencíková1, A. Seifertová1, J. Dérer1, F. Brunner2, J. Würfl2, and J. Kuzmík1
Published in:
phys. stat. sol. (a), vol. 214, no. 11, pp. 1700407 (2017).
Abstract:
The proposal, processing and performance of n+GaN/InGaN/AlGaN/GaN normally-off metal-oxide-semiconductor (MOS) HEMTs with a recessed 2-µm long gate/8-µm source-drain distance are presented. It is shown that by using a negative polarization charge at the InGaN/AlGaN interface together with 10-nm thick Al2O3 gate insulation, a threshold voltage VT increases by 3.6 V reaching a value of ∼1.6 V. Moreover, the combination of the gate recessing through the n+GaN cap and gate insulation lead to an invariant maximal drain current of about 0.25 Amm-1, as well as decreased gate leakage current in the order of ∼10-9 Amm-1. Analytical equations explain the predictive setting of VT up to 7 V with the oxide thickness tox increase, if holes compensate the negative polarization charge. By applying tox = 30 nm a VT ∼3 V was obtained; p-doping of the cap/barrier layers is suggested to reach the theoretically predicted scalability.
1 Institute of Electrical Engineering Slovak Academy of Sciences, Dúbravska cesta 9, 84104 Bratislava, Slovakia
2 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
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