Progress and prospects of group-III nitride semiconductors

Mohammad, S. Noor; Morkoç̌, H.

doi:10.1016/s0079-6727(96)00002-x

Cited by 488 publications

(211 citation statements)

References 400 publications

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“…12 The following material parameters were used: The band gap of Al x Ga 1Ϫx N at room temperature given by E g (x) ϭx6.2 eVϩ(1Ϫx)3.4 eVϪx(1Ϫx)1.0 eV, conductionband offset ⌬E C ϭ0.7͓E g (x)ϪE g (0)͔, 13,14 and dielectric constant ⑀ r (x)ϭ8.9Ϫ0.4x. 15,16 The effect of exchange correlation on Coulomb interaction was neglected, as this has been shown not to affect sheet carrier densities in AlGaN/ GaN heterostructures. 17 The background donor concentration of the GaN and AlGaN layers was set to zero, based on SIMS observations, and on resistivity measurements of nominally undoped GaN grown in our reactor.…”

Section: Methodsmentioning

confidence: 99%

Polarization effects in AlGaN/GaN and GaN/AlGaN/GaN heterostructures

Heikman

Keller

et al. 2003

Journal of Applied Physics

210

130

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The influence of AlGaN and GaN cap layer thickness on Hall sheet carrier density and mobility was investigated for Al 0.32 Ga 0.68 N/GaN and GaN/Al 0.32 Ga 0.68 N/GaN heterostructures deposited on sapphire substrates. The sheet carrier density was found to increase and saturate with the AlGaN layer thickness, while for the GaN-capped structures it decreased and saturated with the GaN cap layer thickness. A relatively close fit was achieved between the measured data and two-dimensional electron gas densities predicted from simulations of the band diagrams. The simulations also indicated the presence of a two-dimensional hole gas at the upper interface of GaN/AlGaN/GaN structures with sufficiently thick GaN cap layers. A surface Fermi-level pinning position of 1.7 eV for AlGaN and 0.9-1.0 eV for GaN, and an interface polarization charge density of 1.6 ϫ10 13 -1.7ϫ10 13 cm Ϫ2 , were extracted from the simulations.

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Section: Methodsmentioning

confidence: 99%

Polarization effects in AlGaN/GaN and GaN/AlGaN/GaN heterostructures

Heikman

Keller

et al. 2003

Journal of Applied Physics

210

130

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“…Semiconductor binary and ternary nitrides and their heterostructures are very promising materials for optical emitters and detectors, and high power/temperature electronic devices 1,2,3 . Nitride semiconductors have been deposited by hydride vapor phase epitaxy (HVPE) 4,5 , and organometallic vapor phase epitaxy (OMVPE) 6,7 , and by molecular beam epitaxy (MBE).…”

Section: Introductionmentioning

confidence: 99%

Characterization of free-standing hydride vapor phase epitaxy GaN

Jasiński

Swider

Liliental‐Weber

et al. 2001

Applied Physics Letters

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A free-standing GaN template grown to a thickness of 300 µm by hydride vapor phase epitaxy (HVPE) has been characterized for its structural properties by transmission electron microscopy (TEM). The TEM investigation was augmented by X-ray diffraction, defect delineation etching process followed by imaging with atomic force microscopy (AFM), and variable temperature photoluminescence (PL). Convergent Beam Electron Diffraction (CBED) was employed to determine the polarity of the free surface and the side juxtaposed to substrate before separation. The substrates side was confirmed to the N-face indicating a growth in the [0001] direction from Ga to N. The density of dislocations near the N-face was determined to be, in order, 3 ± 1 x 10 7 , 4 ± 1 x 10 7 , and about 1 x 10 7 cm -2 as determined by cross-sectional TEM, plan-view TEM and a defect revealing etch, respectively. Identical observations on the Ga-face revealed the defect concentration to be, in order, less than 1 x 10 7 cm -2 by plan-view TEM, 5 x 10 5 cm -2 by cross-sectional TEM, and 5 x 10 5 cm -2 by defect revealing hot H 3 PO 4 acid, respectively. The full width at half maximum (FWHM) of the symmetric (0002) X-ray diffraction peak was 69 and 160 arcsec for the Ga and N-faces, respectively. That for the asymmetric (1014) peak was 103 and 140 arcsec for Ga-and N-faces, respectively. The donor bound exciton linewidth as measured on the Ga and N-face (after the removal of the damage) is about 1 meV each at 10K. Instead of the commonly observed yellow band, this sample displayed a green band, which is centered at about 2.44 eV.

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“…The electron effective mass used here was 0.2m 0 (1Ϫx) ϩ0.48m 0 x for Al x Ga 1Ϫx N, applying Vegard's law. 14,15 According to the theory, it is necessary to use high-frequency dielectric constant, ⑀͑ϱ͒, rather than the low-frequency value, ⑀͑0͒, when the ionization energy is larger than the transverse optical phonon energy. In AlGaN, this occurs when the Al mole fraction is larger than ϳ 80%.…”

mentioning

confidence: 99%

Si doping of high-Al-mole fraction AlxGa1−xN alloys with rf plasma-induced molecular-beam-epitaxy

Hwang

Schaff

Eastman

et al. 2002

Applied Physics Letters

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Very high levels of n-type doping of AlxGa1−xN alloys were recently achieved by rf plasma-induced molecular-beam epitaxy on sapphire substrates and Si as a dopant. Electron concentrations were obtained up to 1.25×1020 cm−3 when the Al mole fraction was 50%, and 8.5×1019 cm−3 electrons were measured even when the Al mole fraction was 80%. Other material properties were determined by optical absorption, photoluminescence, cathodoluminescence, x-ray diffraction, and atomic force microscopy measurements and high optical and morphological qualities were shown.

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Progress and prospects of group-III nitride semiconductors

Cited by 488 publications

References 400 publications

Polarization effects in AlGaN/GaN and GaN/AlGaN/GaN heterostructures

Polarization effects in AlGaN/GaN and GaN/AlGaN/GaN heterostructures

Characterization of free-standing hydride vapor phase epitaxy GaN

Si doping of high-Al-mole fraction AlxGa1−xN alloys with rf plasma-induced molecular-beam-epitaxy

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