GaN-Based Vertical n-Channel MISFETs on Free Standing Ammonothermal GaN Substrates
phys. stat. sol. (a), vol. 215, no. 8, pp. 1700422 (2018).
Copyright © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
In this work, a vertical n-channel MISFET homoepitaxially grown on ammonothermal n-type GaN substrates by MOVPE is demonstrated. The MIS gate module consists of plasma enhanced atomic layer deposition of Al2O3 combined with in-situ NH3 plasma surface pre-treatment. An annealing step performed at 350°C in N2 ambient drastically improves device performance. It reduces the ON-state resistance from ≈12.0 kΩ mm to ≈150 Ω mm, increases the ON-OFF ratio from 106 to 108, and lifts up Ids_max from ≈0.25 to ≈40 mA mm-1. The threshold voltage is above +5 V and the median vertical off-state blocking voltage strength is ≈68 V µm-1. Accumulated C-V characterization of planar MIS-capacitors on n-GaN gives insight to mechanisms boosting device performance after annealing.
1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
2 Wroclawskie Centrum Badan EIT+ Sp. z o.o., ul. Stablowicka 147, 54-066 Wroclaw, Poland
3 SENTECH Instruments GmbH, Schwarzschildstraße 2, 12489 Berlin, Germany
annealing, MISFET, normally-off, PEALD Al2O3, vertical GaN transistors.