Properties and applications of MBE grown AlGaN

Stutzmann, M.; Ambacher, O.; Cros, A.; Brandt, Martin S.; Angerer, H.; Dimitrov, R.; Reinacher, N. M.; Metzger, T. H.; Höpler, R.; Brunner, Daniel; Freudenberg, F.; Handschuh, R.; Deger, Ch

doi:10.1016/s0921-5107(97)00165-7

Cited by 62 publications

(36 citation statements)

References 12 publications

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“…16 The ionization energy data in that report also show a sudden increase in the Si donor ionization energy near 80% Al mole fraction, even though the ionization energy is much smaller, 83 meV in AlN, than 320 meV in the Ref. 12.…”

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confidence: 84%

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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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confidence: 84%

“…9 Figure 3 shows the theoretical Si donor ionization energies in AlGaN with reported experimental data. [10][11][12] TO phonon energies of AlGaN are also shown. 13 From a simple hydrogen model, donor ionization energy of Al x Ga 1Ϫx N increases from 34 meV (xϭ0) to 90 meV (x ϭ1) when low-frequency dielectric constants are used.…”

mentioning

confidence: 93%

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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“…4. Stutzmann and co-workers [14] measured much higher ionization energies for AlGaN alloys with AlN mole fraction of 80% or higher. For example, they reported that the ionization energy of Si in AlN is 320 meV.…”

Section: Resultsmentioning

confidence: 96%

Growth and silicon doping of AlGaN films in the entire alloy composition by molecular beam epitaxy

Thomidis

Friel

et al. 2005

phys. stat. sol. (c)

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In this paper we report the growth and Silicon doping of AlGaN films in the entire alloy composition by RF-plasma-assisted MBE. The films (0.7 to 0.8 µm thick) were grown with the (0001) polarity on C-plane sapphire substrates using a thin AlN buffer and were doped n-type with the silicon cell at a constant temperature (1200 o C). The composition and the structure of the films were determined by XRD, the silicon and oxygen impurities were determined by SIMS measurements, and the transport coefficients were obtained from Hall effect measurements. The FWHM of the on-and off-axis XRD rocking curves indicate that the microstructure of the films is better at low AlN mole fraction (< 20%) and high AlN mole fraction (>70%). The resistivity of the films varies from 10 -3 to 25 Ω.cm as the AlN mole fraction increases from 0 to 96%. Reliable Hall effect measurements were carried out in films with up to 77% Al and were found to be degenerately n-type doped with room temperature carrier concentration varying from 1×10 20 to 7.7×10 18 cm -3 as the AlN mole fraction increased from 0 to 77%. Correspondingly, the electron mobility is reduced by almost an order of magnitude, a result which is consistent with alloy scattering. The effective mass of some of the samples was determined by combining infrared reflectivity and Hall Effect measurements and these data were used to determine the Si ionization energies. We concluded that the Si is the main donor in the entire alloy composition and that the gradual reduction of conductivity with Al content is due to the increase of the Si ionization energy.

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“…The AlGaN E2 phonon line originating from the thin barrier layer was not observed owing its lower cross section and proximity to the GaN E2 peak. 34 Additionally, although they strictly are forbidden in the Z(X-)Z backscattering geometry, the GaN A1(TO) and E1(TO) phonon lines are observed weakly in the Raman spectrum recorded using the SIL, although not in the Raman spectrum recorded using the 0.5 NA lens. The observation of these modes is due to the increased maximum angle of incidence enabled by the SIL, in this case up to 30°, which introduces a significant out-of-plane polarization component.…”

Section: A Electroluminescence Microscopymentioning

confidence: 92%

Solid immersion lenses for enhancing the optical resolution of thermal and electroluminescence mapping of GaN-on-SiC transistors

Pomeroy

Kuball

2015

Journal of Applied Physics

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Solid immersion lenses are shown to greatly enhance optical spatial resolution when measuring AlGaN/GaN HEMTs, taking advantage of the high refractive index of the SiC substrates commonly used for these devices. Solid immersion lenses can be applied to techniques such as electroluminescence emission microscopy and Raman thermography, aiding the development device physics models. Focused ion beam milling is used to fabricate solid immersion lenses in SiC substrates with a numerical aperture of 1.3. A lateral spatial resolution of 300 nm is demonstrated at an emission wavelength of 700 nm and an axial spatial resolution of 1.7±0.3 µm at a laser wavelength of 532 nm is demonstrated; this is an improvement of 2.5× and 5×, respectively, when compared with a conventional 0.5 numerical aperture objective lens without a SIL. These results highlight the benefit of applying the solid immersion lenses technique to the optical characterization of GaN HEMTs. Further improvements may be gained through aberration compensation and increasing the SIL numerical aperture.

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Properties and applications of MBE grown AlGaN

Cited by 62 publications

References 12 publications

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

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

Growth and silicon doping of AlGaN films in the entire alloy composition by molecular beam epitaxy

Solid immersion lenses for enhancing the optical resolution of thermal and electroluminescence mapping of GaN-on-SiC transistors

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