Tuning composition in graded AlGaN channel HEMTs toward improved linearity for low-noise radio-frequency amplifiers
Journal article, 2023
Compositionally graded channel AlGaN/GaN high electron mobility transistors (HEMTs) offer a promising route to improve device linearity, which is necessary for low-noise radio-frequency amplifiers. In this work, we demonstrate different grading profiles of a 10-nm-thick AlxGa1-xN channel from x = 0 to x = 0.1 using hot-wall metal-organic chemical vapor deposition (MOCVD). The growth process is developed by optimizing the channel grading and the channel-to-barrier transition. For this purpose, the Al-profiles and the interface sharpness, as determined from scanning transmission electron microscopy combined with energy-dispersive x-ray spectroscopy, are correlated with specific MOCVD process parameters. The results are linked to the channel properties (electron density, electron mobility, and sheet resistance) obtained by contactless Hall and terahertz optical Hall effect measurements coupled with simulations from solving self-consistently Poisson and Schrödinger equations. The impact of incorporating a thin AlN interlayer between the graded channel and the barrier layer on the HEMT properties is investigated and discussed. The optimized graded channel HEMT structure is found to have similarly high electron density (∼9 × 10 12 cm-2) as the non-graded conventional structure, though the mobility drops from ∼ 2360 cm2/V s in the conventional to ∼ 960 cm2/V s in the graded structure. The transconductance gm of the linearly graded channel HEMTs is shown to be flatter with smaller g m ′ and g m ″ as compared to the conventional non-graded channel HEMT implying improved device linearity.
Author
[Person 1eea4ac1-27e8-4f0b-9945-063795932cd6 not found]
Linköping University
[Person 4da26663-fde4-473d-b622-7ceb54af264f not found]
Linköping University
[Person 7168f560-6cbf-4611-abe0-2d1fd3b24b3b not found]
Lund University
Linköping University
[Person 56ba8dae-dfa3-46ce-a8e8-dc736826adc2 not found]
Linköping University
[Person c9e93daf-7121-46a5-bf3e-b093133bc667 not found]
Linköping University
[Person cbe00de7-2117-410c-94da-64eb94484fe5 not found]
Linköping University
[Person 6ab7eab8-7547-46d5-ab58-093162bed8fa not found]
Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics
[Person b6ce49b4-9906-45f1-9b5b-4d00ad796273 not found]
Saab
Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics
[Person e225eb76-e487-494e-a0fb-65060ac921ce not found]
Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics
[Person aff7d729-d7f4-41cd-8b58-ebf0ffba826d not found]
Linköping University
[Person afbd36d8-2dcb-45cc-ac79-e56c7eafc588 not found]
Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics
[Person 4e6fa857-2330-499f-82f7-32eaa7d22598 not found]
Linköping University
Lund University
Applied Physics Letters
0003-6951 (ISSN) 1077-3118 (eISSN)
Vol. 122 15 153501III-nitrider med låg defekttäthet för grön kraftelektronik
Swedish Foundation for Strategic Research (SSF) (EM16-0024), 2018-01-16 -- 2022-12-31.
Avancerade GaN-komponenter för mm och sub-mmvågs kommunikation
Swedish Foundation for Strategic Research (SSF) (STP19-0008), 2020-06-01 -- 2025-05-31.
Subject Categories (SSIF 2011)
Materials Chemistry
Other Physics Topics
Condensed Matter Physics
DOI
10.1063/5.0141517