Some effects of oxygen impurities on AlN and GaN

Slack, Glen A.; Schowalter, L. J.; Morelli, Donald T.; Freitas, Jaime A.

doi:10.1016/s0022-0248(02)01753-0

Cited by 384 publications

(341 citation statements)

References 54 publications

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“…This is confirmed by the application of the same method (15) to the neutron diffraction data (see Section 3.2) and is consistent with our findings from TEM investigations [23]. The solubility of oxygen in wurtzite gallium nitride has already been researched extensively [7][8][9][10][11][12][13][14] and therefore no further detailed analysis of the nitride phase was performed. Table 3 shows the summary of the refinements, and two typical refined patterns are shown in Fig.…”

Section: X-ray Diffraction Data and Refinementsupporting

confidence: 83%

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On the ammonolysis of Ga2O3: An XRD, neutron diffraction and XAS investigation of the oxygen-rich part of the system Ga2O3–GaN

Roehrens

Brendt

Samuelis

et al. 2010

Journal of Solid State Chemistry

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GaN Ammonolysis Oxynitrides Nitrogen solubility a b s t r a c tWe investigated the ammonolysis of b-Ga 2 O 3 at elevated temperatures by means of ex situ X-ray diffraction, ex situ neutron diffraction and in situ X-ray absorption spectroscopy. Within the detection limits of these methods, we can rule out the existence of a crystalline or amorphous oxynitride phase that is not derived from wurtzite-type GaN. No evidence for a b-Ga 2 O 3 related oxynitride phase was found, and the nitrogen solubility in b-Ga 2 O 3 was found to be below the detection limit of about 2-3 at% in the anionic sublattice. These findings were obtained by monitoring the anionic occupancy factors and the lattice parameters of the b-Ga 2 O 3 phase obtained from total diffraction pattern refinement with the Rietveld method and by linear combination fitting of the X-ray absorption spectra that were recorded during the ammonolysis.

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Section: X-ray Diffraction Data and Refinementsupporting

confidence: 83%

“…These oxynitrides are characterized as being derived from wurtzite-type GaN, with dissolved oxygen in the anionic sublattice. It is known, that the anion sublattice of GaN can accommodate up to 30 at% of oxygen, which is-according to the literature-compensated by electrons [6][7][8][9][10][11][12][13] and/or gallium vacancies [14].…”

Section: Introductionmentioning

confidence: 99%

On the ammonolysis of Ga2O3: An XRD, neutron diffraction and XAS investigation of the oxygen-rich part of the system Ga2O3–GaN

Roehrens

Brendt

Samuelis

et al. 2010

Journal of Solid State Chemistry

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“…The lattice distortion due to aluminium vacancies resulting from incorporation of oxygen into the lattice leads to increased phonon scattering, thus lowering the thermal conductivity of the material [25,[42][43][44][45][46].…”

Section: Aluminium Nitridementioning

confidence: 99%

A review of the processing, composition, and temperature-dependent mechanical and thermal properties of dielectric technical ceramics

et al. 2011

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The current review uses the material requirements of a new space propulsion device, the Variable Specific Impulse Magnetoplasma Rocket (VASIMR ® ) as a basis for presenting the temperature dependent properties of a range of dielectric ceramics, but data presented could be used in the engineering design of any ceramic component with complementary material requirements. A material is required for the gas containment tube (GCT) of VASIMR ® to allow it to operate at higher power levels. The GCT's operating conditions place severe constraints on the choice of material. A dielectric is required with a high thermal conductivity, low dielectric loss factor, and high thermal shock resistance. There is a lack of a representative set of temperature-dependent material property data for materials considered for this application and these are required for accurate thermo-structural modelling. This modelling would facilitate the selection of an optimum material for this component. The goal of this paper is to determine the best material property data values for use in the materials selection and design of such components. A review of both experimentally and theoretically-determined temperature-dependent & room temperature properties of several materials has been undertaken. Data extracted are presented by property. Properties reviewed are density, Young's, bulk and shear moduli, Poisson's ratio, tensile, flexural and compressive strength, thermal conductivity, specific heat capacity, thermal expansion coefficient and the factors affecting maximum service temperature. Materials reviewed are alumina, aluminium nitride, beryllia, fused quartz, sialon and silicon nitride.

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“…As a function of the substrate electrode temperature, the value varies around 150 meV up to 300°C, possibly decreasing slightly, before increasing rapidly to 470 meV at 375°C and to 840 meV at 450°C. Slack et al 36 have suggested that the Urbach tail could be caused by O impurities. Figure 7͑a͒ shows how the spectral features of films deposited at higher temperatures and O content tend to be smeared out.…”

Section: Urbach Tail Energymentioning

confidence: 99%

The properties and deposition process of GaN films grown by reactive sputtering at low temperatures

Knox-Davies

Shannon

Silva

2006

Journal of Applied Physics

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Polycrystalline gallium nitride films, 100 nm to 1 m thick, were deposited under a range of conditions. Substrate electrode temperatures during sputtering were varied from room temperature to 450°C, the pressure from 0.15 to 6.0 Pa, the nitrogen fraction of the deposition atmosphere from 10% to 100% and the target bias from −400 to − 1800 V. The deposition rates as functions of these conditions are in the range 0.5-25 nm/ min. The growth rate is considered to be controlled respectively by the thermally activated desorption from the substrate, changes in the mean free path and concentration of gas particles, differences between the sputter yields of Ga and GaN in Ar and N 2 , and changes in the ion current and sputter yields. The films are generally columnar, with the grain size increasing with film thickness. The most crystalline films were grown at mid range temperatures, low N 2 concentrations, and low target biases, and the most disordered were grown at low pressures. The latter two cases suggest that decreasing the energy of particles incident on the film during deposition results in a more ordered film. The biaxial stress is compressive and shows an increasing trend with the target bias and N 2 concentration, reaching 4.7 GPa at 75% N 2 . Oxygen contamination of 3 -30 at. % has a major effect on the optical properties of the films, increasing the band gap values from 3.02 to Ͼ 4.0 eV and the Urbach tail energies from around 150 to 840 meV and decreasing the refractive index from 2.46 to 2.03. At a 40% N 2 deposition fraction, the N:Ga ratio is more or less constant at 1:1. Since the absolute oxygen incorporation rate changes very little, it is the relative film deposition rate which determines the final oxygen concentration. Excess Ga at low N 2 concentrations causes a decrease in the band gap and an increase in the Urbach tail energy.

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Some effects of oxygen impurities on AlN and GaN

Cited by 384 publications

References 54 publications

On the ammonolysis of Ga2O3: An XRD, neutron diffraction and XAS investigation of the oxygen-rich part of the system Ga2O3–GaN

On the ammonolysis of Ga2O3: An XRD, neutron diffraction and XAS investigation of the oxygen-rich part of the system Ga2O3–GaN

A review of the processing, composition, and temperature-dependent mechanical and thermal properties of dielectric technical ceramics

The properties and deposition process of GaN films grown by reactive sputtering at low temperatures

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