Preparation and lithium doping of gallium oxynitride by ammonia nitridation via a citrate precursor route

Journal Article · Sun Jul 15 00:00:00 EDT 2007 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2007.04.011· OSTI ID:21015863

Kikkawa, Shinichi ^[1]; Nagasaka, Kazuteru ^[1]; Takeda, Takashi ^[1]; Bailey, Mark ^[1]; Sakurai, Toshitaka ^[2]; Miyamoto, Yoshinari ^[2]

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1. Graduate School of Engineering, Hokkaido University, N13W8, Kita-ku Sapporo 060-8628 (Japan)
2. Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

Gallium oxynitride, isostructural to hexagonal gallium nitride (h-GaN), was obtained by ammonia nitridation of a precursor prepared from the addition of citric acid to an aqueous solution of gallium nitrate. Gallium oxynitride produced at 750 deg. C had a small amount of gallium vacancies, and was formulated as (Ga{sub 0.89}{open_square}{sub 0.11}) (N{sub 0.66}O{sub 0.34}) where the symbol {open_square} stands for gallium vacancy. Both the gallium vacancies and oxygen substituted for nitrogen were randomly distributed within the structure. The amount of vacancies decreased with nitridation temperatures in the range of 750-850 deg. C. Approximately, 10 at% Li{sup +} was doped into the gallium oxynitride, using a similar preparation with the additional presence of lithium nitrate, resulted in the random substitution of Ga{sup 3+} in an atomic ratio of Li/Ga<1 at 750 deg. C. Oxygen was codoped with lithium and substituted nitrogen in the wurtzite-type crystal lattice. These substitutions reduced the electrical conductivity in the gallium oxynitride semiconductor. A new oxynitride, Li{sub 2}Ga{sub 3}NO{sub 4}, was also obtained with Li{sub 2}CN{sub 2} impurity using similar preparations from a mixture of Li/Ga{>=}1. The crystal structure was isostructural with h-GaN, and was refined as P6{sub 3} mc with a=0.31674(1) nm, and c=0.50854(2) nm. The Ga and Li occupancies at the 2b site were refined to be 0.6085 and 0.3915, respectively, assuming that the other 2b site was randomly occupied with 1/5O and 4/5N. When the new compound was washed for over 1 min for the removal of Li{sub 2}CN{sub 2} impurities, it was decomposed to a mixture of {alpha}-GaOOH and {alpha}-LiGaO{sub 2}. The as-prepared product with Li/Ga=1 showed the highest intensity in yellow luminescence among the products under excitation at 254 nm. - Graphical abstract: Schematic gallium vacancy distribution within a Ga-plane in wurtzite-type gallium oxynitride prepared via a citrate precursor route. Closed and open circles represent gallium and its vacancy sites, respectively. This is the most probable case among various kinds of statistical vacancy distribution, where Ga/vacancy=6/1 in atomic ratio. About 10 at% Li{sup +} could be doped to the gallium oxynitride by substituting Ga{sup 3+}. Well-crystallized new oxynitride, Li{sub 2}Ga{sub 3}NO{sub 4}, isostructural with h-GaN, was also obtained in the preparation with Li/Ga{>=}1.

• OSTI ID: 21015863
• Journal Information: Journal of Solid State Chemistry, Vol. 180, Issue 7; Other Information: DOI: 10.1016/j.jssc.2007.04.011; PII: S0022-4596(07)00161-2; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
AMMONIA
AQUEOUS SOLUTIONS
CITRATES
CITRIC ACID
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
GALLIUM IONS
GALLIUM NITRATES
GALLIUM NITRIDES
HEXAGONAL LATTICES
LITHIUM IONS
LITHIUM NITRATES
LUMINESCENCE
NITRIDATION
OXYGEN COMPOUNDS
SEMICONDUCTOR MATERIALS
VACANCIES