On the nature of the oxygen-related defect in aluminum nitride

Harris, J. H.; Youngman, R. A.; Teller, Raymond G.

doi:10.1557/jmr.1990.1763

Cited by 233 publications

(123 citation statements)

References 31 publications

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“…PL caused by intrinsic defects such as vacancies, O impurities, and their complexes in AlN is well known. [22][23][24][25] AlN is extremely susceptible to O contamination, so O impurities are typically considered intrinsic. Studies on AlN ceramics 22,23 observed a PL peak in the ∼300 to 375 nm region and attributed it to an O related defect complex [V A1 -O N · ].…”

Section: -5mentioning

confidence: 99%

Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

et al. 2016

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We introduce high thermal conductivity aluminum nitride (AlN) as a transparent ceramic host for Ce3+, a well-known active ion dopant. We show that the Ce:AlN ceramics have overlapping photoluminescent (PL) emission peaks that cover almost the entire visible range resulting in a white appearance under 375 nm excitation without the need for color mixing. The PL is due to a combination of intrinsic AlN defect complexes and Ce3+ electronic transitions. Importantly, the peak intensities can be tuned by varying the Ce concentration and processing parameters, causing different shades of white light without the need for multiple phosphors or light sources. The Commission Internationale de l’Eclairage coordinates calculated from the measured spectra confirm white light emission. In addition, we demonstrate the viability of laser driven white light emission by coupling the Ce:AlN to a readily available frequency tripled Nd-YAG laser emitting at 355 nm. The high thermal conductivity of these ceramic down-converters holds significant promise for producing higher power white light sources than those available today.

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Section: -5mentioning

confidence: 99%

Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

et al. 2016

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“…The thermal conductivity of AlN ceramics is greatly affected by the presence of metallic impurities [38], and oxygen impurity [39][40][41] present on the surface of the starting AlN powder in the form of Al 2 O 3 due to spontaneous reaction with air, and also dissolved in the AlN lattice. 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%

“…At room temperature, oxygen-related defects are the dominant mechanism limiting the thermal conductivity of AlN [22,40], but their effect decreases at elevated temperatures [24]. Metallic impurities also have the effect of greatly reducing the RT thermal conductivity [38].…”

Section: Thermal Conductivitymentioning

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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“…11,12 Oxygen adversely affects the properties, crystal quality, and surface morphology of the AlN crystals. [13][14][15][16] At low concentrations, oxygen promotes the formation of Al vacancies which significantly reduces AlN's thermal conductivity. 13 With increasing oxygen concentration and hence Al vacancy concentrations, the Al vacancies coalesce, forming stacking faults, inversion domains, and more extended defects.…”

Section: 10mentioning

confidence: 99%

Native oxide and hydroxides and their implications for bulk AlN crystal growth

Edgar

Nyakiti

et al. 2008

Journal of Crystal Growth

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Oxygen degrades the properties of AlN, thus producing bulk single crystals with low oxygen concentrations is an important goal. Most of the oxygen in bulk AlN single crystals grown by the sublimation-recondensation method originates from the hydroxides and oxides that spontaneously form on the surfaces of the AlN source powder. For a typical AlN powder with an average particle size of 1-2 microns, a 1-3 nm thick oxide and/or hydroxide can account for most of its oxygen (generally on the order of 1.0 wt%) and hydrogen (200-300 ppm). Heating the AlN powder source at 1950 °C for 10 h in a nitrogen atmosphere reduced its surface area by a factor of 160 (due to sintering), the oxygen concentration by 16, and the hydrogen concentration by 67. The difference in these reduction factors suggests some of the oxygen is dissolved into the bulk AlN with this heat treatment. By first annealing the AlN powder at a low temperature (950-1000 °C) for several hours before sintering at 1950 °C, the oxygen and hydrogen concentrations were reduced to lower levels. The low temperature treatment is effective eliminating oxygen and hydrogen from the surface of the powder, while high temperature sintering reduces the specific surface area of the source. The combination of heat treatments produced a source with oxygen and hydrogen concentrations as low as 0.015 wt% O (1.9 x 10 19 atoms O cm -3 ) and 1.7 ppm H (3.4 x 10 18 atoms H cm -3 ). Annealing becomes less effective at removing oxygen and hydrogen with longer heat treatments, suggesting there is a minimum oxygen concentration that can be produced with this method.

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On the nature of the oxygen-related defect in aluminum nitride

Cited by 233 publications

References 31 publications

Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

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

Native oxide and hydroxides and their implications for bulk AlN crystal growth

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