N-polar AlGaN HEMTs on silicon for reduced contact resistance
Abstract
Nitrogen-polar (N-polar) AlGaN-channel high electron mobility transistors (HEMTs) offer a promising pathway to overcome the limitations of equivalent metal-polar (M-polar) devices, particularly the high contact resistance associated with increased aluminum content. In this work, we report the growth and fabrication of N-polar AlGaN-channel HEMTs on a silicon substrate by ammonia molecular beam epitaxy (NH3-MBE). N-polarity is achieved using an epitaxial NbN polarity-inversion layer, enabling the growth of a buffer stack with adequate structural and electrical quality. Two heterostructure designs are investigated. Capacitance–voltage and Hall measurements confirm the formation of a high-density two-dimensional electron gas with sheet carrier densities up to 2.4×1013 cm−2. Owing to the elimination of the Al-rich barrier between the surface and the channel (present in M-polar configuration) and improving surface morphology, encouraging low-resistance Ohmic contacts are achieved, with contact resistance reduced below 1 Ω mm on the Al0.2Ga0.8N channel. These results demonstrate the viability of N-polar AlGaN-channel HEMTs on silicon and highlight their potential for next-generation ultra-wide-bandgap power devices on Si.
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BibTeX
@article{barbiercueil2026npolar,
title = {{N-polar AlGaN HEMTs on silicon for reduced contact resistance}},
author = {A. Barbier-Cueil and J. Mehta and A. Pédèches and F. Medjdoub and F. Semond},
journal = {Applied Physics Letters},
year = {2026},
month = jun,
doi = {10.1063/5.0329237},
url = {https://hal.science/hal-05678244v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - N-polar AlGaN HEMTs on silicon for reduced contact resistance
AU - A. Barbier-Cueil
AU - J. Mehta
AU - A. Pédèches
AU - F. Medjdoub
AU - F. Semond
PY - 2026
DA - 2026/06/29
JO - Applied Physics Letters
DO - 10.1063/5.0329237
UR - https://hal.science/hal-05678244v1
AB - Nitrogen-polar (N-polar) AlGaN-channel high electron mobility transistors (HEMTs) offer a promising pathway to overcome the limitations of equivalent metal-polar (M-polar) devices, particularly the high contact resistance associated with increased aluminum content. In this work, we report the growth and fabrication of N-polar AlGaN-channel HEMTs on a silicon substrate by ammonia molecular beam epitaxy (NH3-MBE). N-polarity is achieved using an epitaxial NbN polarity-inversion layer, enabling the growth of a buffer stack with adequate structural and electrical quality. Two heterostructure designs are investigated. Capacitance–voltage and Hall measurements confirm the formation of a high-density two-dimensional electron gas with sheet carrier densities up to 2.4×1013 cm−2. Owing to the elimination of the Al-rich barrier between the surface and the channel (present in M-polar configuration) and improving surface morphology, encouraging low-resistance Ohmic contacts are achieved, with contact resistance reduced below 1 Ω mm on the Al0.2Ga0.8N channel. These results demonstrate the viability of N-polar AlGaN-channel HEMTs on silicon and highlight their potential for next-generation ultra-wide-bandgap power devices on Si.
SN - 0003-6951
SN - 1077-3118
ER -