AlGaN/GaN microwave HFET including a thin AlN carrier exclusion layer

Balmer, R.S.; Hilton, K.P.; Nash, K.J.; Uren, Michael J.; Wallis, D. J.; Wells, A.; Missous, M.; Martin, T.

doi:10.1002/pssc.200303310

Cited by 25 publications

(16 citation statements)

References 10 publications

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“…In this case, the results from the computations [30] and the experiments [31][32] show in good agreement to each other that the room-temperature 2DEG mobility is eventually limited below 2500 cm 2 /V-s.…”

Section: Transport Properties Of 2degsupporting

confidence: 77%

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MOCVD growth of GaN-based high electron mobility transistor structures

Chen¹

2015

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IICover: surface morphology of a GaN high electron mobility transistor structure grown on a native GaN substrate. The image was obtained with an atomic force microscope. AbstractWide bandgap group-III nitride semiconductors like GaN, AlN, and their alloys are very suitable for the use in high-power, high-frequency electronics, as a result of their superior intrinsic properties. The polarization-induced high-density and high-mobility two-dimensional electron gas (2DEG) forming in (0001) oriented AlGaN/GaN heterostructures enable the epitaxial structure to be utilized for high electron mobility transistors (HEMTs). Outstanding power handling and record high frequency have been demonstrated from GaN-based HEMT devices over time. However, the shortterm stability and the long-term reliability of the device performances remain problematic. In order to make GaN HEMT technology truly take off and breach the civilian market like automotive, telecommunication applications, the problems need to be solved to justify its relatively high cost over the solutions based on Si and GaAs technologies.At the material level, there are two major challenges; one is the reduction of highdensity structural defects in heteroepitaxially grown layers when foreign substrates are used, and the other is the control of "deep" electron traps forming in the middle of the "wide" bandgap by intrinsic defects or extrinsic impurities.The main idea of the present work was therefore to tackle these material issues directly, using an approach called bottom-to-top optimization to improve the overall quality of GaN-based HEMT epitaxial structures grown on semi-insulating (SI) SiC and native GaN substrates. The bottom-to-top optimization means an entire growth process optimization, from in-situ substrate pretreatment to the epitaxial growth and then the cooling process. Great effort was put to gain the understanding of the influence of growth parameters on material properties and consequently to establish an advanced and reproducible growth process. Many state-of-the-art material properties of GaNbased HEMT structures were achieved in this work, including superior structural integrity of AlN nucleation layers for ultra-low thermal boundary resistance, excellent control of residual impurities, outstanding and nearly-perfect crystalline quality of GaN epilayers grown on SiC and native GaN substrates, respectively, and record-high room temperature 2DEG mobility obtained in simple AlGaN/GaN heterostructures.The epitaxial growth of the wide bandgap III-nitride epilayers like GaN, AlN, AlGaN, and InAlN, as well as various GaN-based HEMT structures was all carried out in a hot-wall metalorganic chemical vapor deposition (MOCVD) system. A variety of structural and electrical characterizations were routinely used to provide fast feedback VI for adjusting growth parameters and developing improved growth processes, such as optical microscopy (OM), atomic force microscopy (AFM), x-ray diffraction (XRD), capacitance-voltage measurement (CV) as well as sheet resistance...

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Section: Transport Properties Of 2degsupporting

confidence: 77%

“…This proposal was based on their calculations that the penetration depth of electrons into AlN would be only 3 Å. Just few years later, room-temperature 2DEG mobility above 2000 cm 2 /V-s was then realized for the first time using the AlGaN/AlN/GaN heterostructure as proposed [31].…”

Section: (B) Alloy Disordermentioning

confidence: 99%

MOCVD growth of GaN-based high electron mobility transistor structures

Chen¹

2015

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“…3,4 By inserting a thin (1-2 nm) AlN exclusion layer (AlN ex ) at the AlGaN/GaN interface, the 2DEG mobility can be remarkably increased to $2200 cm 2 /VÁs. [5][6][7] This mobility improvement is associated with better 2DEG confinement near the interface, reducing the penetration of the electron wave function into the AlGaN barrier, so that the scattering due to alloy disorder is alleviated. 8 However, the presence of the thin AlN ex layer (or high-Al-content AlGaN layer) can raise the surface potential in a HEMT structure owing to its wide band gap nature, rendering difficulties in obtaining low ohmic contact resistance, 9 which is essential for high-frequency applications.…”

mentioning

confidence: 99%

Room-temperature mobility above 2200 cm2/V·s of two-dimensional electron gas in a sharp-interface AlGaN/GaN heterostructure

Chen

Persson

Nilsson

et al. 2015

Applied Physics Letters

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“…To produce high-quality devices, a high product of electron mobility, m, and times carrier concentration, n s , is critical. Recently, a promising AlGaN/ AlN/GaN HEMT structure has proved to be highly effective in improving both the electron mobility and concentration [1][2][3]. Miyoshi et al [3] achieved a 2DEG mobility of 2174 cm 2 /V s at room temperature with the carrier density of 0.95 Â 10 13 cm À2 in Al 0.26 Ga 0.72 N/AlN/ GaN structures deposited by metalorganic vapor phase epitaxy (MOVPE) on epitaxial AlN/sapphire templates.…”

Section: Introductionmentioning

confidence: 99%

MOCVD-grown high-mobility Al0.3Ga0.7N/AlN/GaN HEMT structure on sapphire substrate

Wang

et al. 2007

Journal of Crystal Growth

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AlGaN/GaN microwave HFET including a thin AlN carrier exclusion layer

Cited by 25 publications

References 10 publications

MOCVD growth of GaN-based high electron mobility transistor structures

MOCVD growth of GaN-based high electron mobility transistor structures

Room-temperature mobility above 2200 cm2/V·s of two-dimensional electron gas in a sharp-interface AlGaN/GaN heterostructure

MOCVD-grown high-mobility Al0.3Ga0.7N/AlN/GaN HEMT structure on sapphire substrate

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