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Polarization‐Engineered n + GaN/InGaN/AlGaN/GaN Normally‐Off MOS HEMTs
Author(s) -
Gregušová Dagmar,
Blaho Michal,
Haščík Štefan,
Šichman Peter,
Laurenčíková Agáta,
Seifertová Alena,
Dérer Ján,
Brunner Frank,
Würfl Joachim,
Kuzmík Ján
Publication year - 2017
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201700407
Subject(s) - materials science , optoelectronics , wide bandgap semiconductor , gallium nitride , polarization (electrochemistry) , doping , threshold voltage , voltage , transistor , electrical engineering , layer (electronics) , nanotechnology , chemistry , engineering
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 Al 2 O 3 gate insulation, a threshold voltage V T 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 A mm −1 , as well as decreased gate leakage current in the order of ∼10 −9 A mm −1 . Analytical equations explain the predictive setting of V T up to 7 V with the oxide thickness t ox increase, if holes compensate the negative polarization charge. By applying t ox = 30 nm a V T ∼ 3 V was obtained; p‐doping of the cap/barrier layers is suggested to reach the theoretically predicted scalability.