• Journal of the Korean Ceramic Society
• /
• v.40 no.11
• /
• pp.1058-1061
• /
• 2003

Gallium Nitride (GaN) powders were synthesized by calcining a gallium(III) sulfate salt in flowing ammonia in the temperature range 500-1100$^{\circ}C$. The process of conversion of the salt to GaN was monitored by X-Ray Diffraction (XRD). The salt decomposed to ${\gamma}$-Ga$_2$O$_3$ and then converted to GaN without ${\gamma}$-${\beta}$Ga$_2$O$_3$ phase transition. Variations in XRD patterns and weight loss of samples with temperature indicate that the conversion of ${\gamma}$-Ga$_2$O$_3$ to GaN does not proceed through Ga$_2$O but stepwise via amorphous gallium oxynitride (GaO$\_$x/N$\_$y/) as intermediates. Room-temperature photoluminescence spectra of GaN powders obtained showed the emission peak at 363 nm and no yellow band.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.2
• /
• pp.343-344
• /
• 2005

• Bulletin of the Korean Chemical Society
• /
• v.26 no.1
• /
• pp.131-135
• /
• 2005

Gallium nitride (GaN) powders and nanowires were prepared by using tris(N,N-dimethyldithiocarbamato)gallium(III) (Ga(DmDTC)$_3$) and tris(N,N-diethyldithiocarbamato)gallium(III) (Ga(DeDTC)$_3$) as new precursors. The GaN powders were obtained by reaction of the complexes with ammonia in the temperature ranging from 500 to 1100 ${^{\circ}C}$. The process of conversion of the complexes to GaN was monitored by their weight loss, XRD, and $^{71}$Ga magic-angle spinning (MAS) NMR spectroscopy. Most likely the complexes decompose to $\gamma$ -Ga$_2$S$_3$ and then turn into GaN via amorphous gallium thionitrides (GaS$_x$N$_y$). The reactivity of Ga(DmDTC)$_3$ with ammonia was a little higher than that of Ga(DeDTC)$_3$. Room-temperature photoluminescence spectra of asprepared GaN powders exhibited the band-edge emission of GaN at 363 nm. GaN nanowires were obtained by nitridation of as-ground $\gamma$ -Ga$_2$S$_3$ powders to GaN powders, followed by sublimation without using templates or catalysts.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.1
• /
• pp.51-54
• /
• 2004

Gallium nitride (GaN) powders were prepared by calcining a gallium(III) nitrate salt in flowing ammonia in the temperature ranging from 500 to 1050 $^{\circ}C$. The process of conversion of the salt to GaN was monitored by X-ray diffraction and $^{71}Ga$ MAS (magic-angle spinning) NMR spectroscopy. The salt decomposed to ${\gamma}-Ga_2O_3$ and then converted to GaN without ${\gamma}-{\beta}Ga_2O_3$ phase transition. It is most likely that the conversion of ${\gamma}-Ga_2O_3$ to GaN does not proceed through $Ga_2O$ but stepwise via amorphous gallium oxynitride ($GaO_xN_y$) as intermediates. The GaN nanowires and microcrystals were obtained by calcining the pellet containing a mixture of ${\gamma}-Ga_2O_3$ and carbon in flowing ammonia at 900 $^{\circ}C$ for 15 h. The growth of the nanowire might be explained by the vapor-solid (VS) mechanism in a confined reactor. Room-temperature photoluminescence spectra of as-synthesized GaN powders obtained showed the emission peak at 363 nm.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.2
• /
• pp.372-376
• /
• 2008

The hydrolysis of gallium(III) has been studied using potentiometric techniques under physiological conditions of temperature 37 C and ionic strength 0.15 moldm-3 NaCl and at different metal ion concentrations. Changes in pH were monitored with a glass electrode calibrated daily in hydrogen ions concentrations. The titration data within the pH range of 2.5-9.99 were analyzed to determine stability constants of hydroxide species using the SUPERQUAD program. Several different species were considered during the calculation procedure and the following hydroxides have been characterized: Ga(OH)3, Ga(OH)4- Ga3(OH)112-, Ga4(OH)11+ and Ga6(OH)153+. Speciation calculations based on the determined constants were then used to simulate the species distribution.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.2
• /
• pp.127-137
• /
• 2004

We have investigated the structures, the energetic, and the nanomechanics of the single-wall boron-, aluminum-, and gallium-nitride nanotubes using atomistic simulations based on the Tersoff-type potential. The Tersoff-type potential for the III-nitride materials has effectively described the properties of the III-nitride nanotubes. Nanomechanics of boron-, aluminum-, and gallium-nitride nanotubes under the compression loading has been investigated and their Young's moduli were calculated.

• Analytical Science and Technology
• /
• v.6 no.1
• /
• pp.131-139
• /
• 1993

The separation of gallium and indium from the matrix elements such as zinc and other ions, especially form Fe(III) ion was studied for the determination of trace level of them in zinc ores and zinc blendes by inductively coupled plasma atomic emission spectrometry(ICP-AES). Gallium and indium were extracted from the sample solution with a solvent of tributyl phosphate(TBP). The type and concentration of acid, interferences of other ions, the ratio of aqueous phase to organic phase, TBP concentration, sripping efficiency were optimized for the effective extraction. Gallium and indium were separated from other ions in the 5N hydrochloric acid solution of the samples by the extraction with 100% TBP. In this time, Fe(III) was reduced to Fe(II) with hydroxylamine hydrochloride to prevent its coextraction prior to the main extraxtion. After stripped from organic phase by the back-extraction with 0.02N HCl, they were determined in the aqueous phase by ICP-AES. This method was known to be quantitative from the overall extraction of more than 95%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.6
• /
• pp.446-450
• /
• 2013

Growth mechanism of GS-MBE(Gas source-Molecular Beam Epitaxy) has been investigated. We observed that the growth rate of GaN films is changing from 520 nm/h to 440 nm/h by the variation of V/III ratio under nitrogen-rich growth condition. It was explained that the amount of hydrogen on the growth front varies by the ammonia flow, and gallium hydrides are generated on the surface by a reaction of hydrogen and gallium, resultantly the amount of gallium supplying is changing along with the $NH_3$ flow. Reflection high energy electron diffraction (RHEED) observation was used to confirm the N-rich condition. The crystal quality of GaN was estimated by photoluminescence (PL) and X-ray diffraction (XRD).

• Resources Recycling
• /
• v.2 no.4
• /
• pp.27-32
• /
• 1993

A process has been studied to recover gallium from steelmaking dust which had several hundreds ppm of gallium. Aqueous solution containing 38 mg/l gallium was obtained by leaching of dust with 2.25 mol/l sulfuric acid. The leach liquor contained iron and zinc about 1,000 times greater than gallium. Gallium was then concentrated by ion exchanger of chelating resin with functional group of amino carboxylic acid after reduction of ferric ion to ferrous ion and pH adjustment. Gallium was concentrated to be 13 g/l in the resulting eluate by double ion exchanges. The liquor was further treated to remove impurities by solvent extraction technique empolying TOMAC as extractant. The galluim with 99% purity was finally obtainable.

• Journal of Power Electronics
• /
• v.9 no.1
• /
• pp.36-42
• /
• 2009

This paper presents a review of an improved high power-high frequency III-V wide bandgap (WBG) semiconductor device, Gallium Nitride (GaN). The device offers better efficiency and thermal management with higher switching frequency. By having higher blocking voltage, GaN can be used for high voltage applications. In addition, the weight and size of passive components on the printed circuit board can be reduced substantially when operating at high frequency. With proper management of thermal and gate drive design, the GaN power converter is expected to generate higher power density with lower stress compared to its counterparts, Silicon (Si) devices. The main contribution of this work is to provide additional information to young researchers in exploring new approaches based on the device's capability and characteristics in applications using the GaN power converter design.