The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates

A. Sedhain; L. Du; J. H. Edgar; J. Y. Lin; H. X. Jiang

doi:10.1063/1.3276567

The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates

A. Sedhain, L. Du, J. H. Edgar, J. Y. Lin, H. X. Jiang

Electrical and Computer Engineering

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54 Scopus citations

Abstract

The yellow color of bulk AlN crystals was found to be caused by the optical absorption of light with wavelengths shorter than that of yellow. This yellow impurity limits UV transparency and hence restricts the applications of AlN substrates for deep UV optoelectronic devices. Here, the optical properties of AlN epilayers, polycrystalline AlN, and bulk AlN single crystals have been investigated using photoluminescence (PL) spectroscopy to address the origin of this yellow appearance. An emission band with a linewidth of ∼0.3 eV (at 10 K) was observed at ∼2.78 eV. We propose that the origin of the yellow color in bulk AlN is due to a band-to-impurity absorption involving the excitation of electrons from the valence band to the doubly negative charged state, (V _Al^2-), of isolated aluminum vacancies, (VAl) ^3-/2- described by V_Al^2-+hν= V _Al^3-+h⁺. In such a context, the reverse process is responsible for the 2.78 eV PL emission.

Original language	English
Article number	262104
Journal	Applied Physics Letters
Volume	95
Issue number	26
DOIs	https://doi.org/10.1063/1.3276567
State	Published - 2009

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@article{a8b826e7321b42b28ad1e5179e704827,

title = "The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates",

abstract = "The yellow color of bulk AlN crystals was found to be caused by the optical absorption of light with wavelengths shorter than that of yellow. This yellow impurity limits UV transparency and hence restricts the applications of AlN substrates for deep UV optoelectronic devices. Here, the optical properties of AlN epilayers, polycrystalline AlN, and bulk AlN single crystals have been investigated using photoluminescence (PL) spectroscopy to address the origin of this yellow appearance. An emission band with a linewidth of ∼0.3 eV (at 10 K) was observed at ∼2.78 eV. We propose that the origin of the yellow color in bulk AlN is due to a band-to-impurity absorption involving the excitation of electrons from the valence band to the doubly negative charged state, (V Al2-), of isolated aluminum vacancies, (VAl) 3-/2- described by VAl2-+hν= V Al3-+h+. In such a context, the reverse process is responsible for the 2.78 eV PL emission.",

author = "A. Sedhain and L. Du and Edgar, {J. H.} and Lin, {J. Y.} and Jiang, {H. X.}",

note = "Funding Information: This work is supported by DOE under Grant no. FG02-09ER46552. H.X.J. and J.Y.L. would like to acknowledge the support of Edward Whitacre and Linda Whitacre endowed chairs through the AT&T foundation.",

year = "2009",

doi = "10.1063/1.3276567",

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volume = "95",

journal = "Applied Physics Letters",

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T1 - The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates

AU - Sedhain, A.

AU - Du, L.

AU - Edgar, J. H.

AU - Lin, J. Y.

AU - Jiang, H. X.

N1 - Funding Information: This work is supported by DOE under Grant no. FG02-09ER46552. H.X.J. and J.Y.L. would like to acknowledge the support of Edward Whitacre and Linda Whitacre endowed chairs through the AT&T foundation.

PY - 2009

Y1 - 2009

N2 - The yellow color of bulk AlN crystals was found to be caused by the optical absorption of light with wavelengths shorter than that of yellow. This yellow impurity limits UV transparency and hence restricts the applications of AlN substrates for deep UV optoelectronic devices. Here, the optical properties of AlN epilayers, polycrystalline AlN, and bulk AlN single crystals have been investigated using photoluminescence (PL) spectroscopy to address the origin of this yellow appearance. An emission band with a linewidth of ∼0.3 eV (at 10 K) was observed at ∼2.78 eV. We propose that the origin of the yellow color in bulk AlN is due to a band-to-impurity absorption involving the excitation of electrons from the valence band to the doubly negative charged state, (V Al2-), of isolated aluminum vacancies, (VAl) 3-/2- described by VAl2-+hν= V Al3-+h+. In such a context, the reverse process is responsible for the 2.78 eV PL emission.

AB - The yellow color of bulk AlN crystals was found to be caused by the optical absorption of light with wavelengths shorter than that of yellow. This yellow impurity limits UV transparency and hence restricts the applications of AlN substrates for deep UV optoelectronic devices. Here, the optical properties of AlN epilayers, polycrystalline AlN, and bulk AlN single crystals have been investigated using photoluminescence (PL) spectroscopy to address the origin of this yellow appearance. An emission band with a linewidth of ∼0.3 eV (at 10 K) was observed at ∼2.78 eV. We propose that the origin of the yellow color in bulk AlN is due to a band-to-impurity absorption involving the excitation of electrons from the valence band to the doubly negative charged state, (V Al2-), of isolated aluminum vacancies, (VAl) 3-/2- described by VAl2-+hν= V Al3-+h+. In such a context, the reverse process is responsible for the 2.78 eV PL emission.

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DO - 10.1063/1.3276567

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VL - 95

JO - Applied Physics Letters

JF - Applied Physics Letters

IS - 26

M1 - 262104

ER -

The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates

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