Chemical Deposition of Rodlike GaOOH and β-Ga[sub 2]O[sub 3] Films Using Simple Aqueous Solutions

Abstract

Rodlike GaOOH particles and films were successfully prepared in a large scale from a simple aqueous gallium nitrate solution. First, a hydrothermal treatment of the solution at 150°C led to the formation of GaOOH rods, and their subsequent heat-treatments at 700°C promoted transformation into ␤-Ga 2 O 3 having the similar particle morphology. Second, using the same aqueous solutions, strongly c-axis-oriented GaOOH films consisting of rodlike particles could be deposited on substrates through chemical solution processes. It was found that heterogeneous nucleation of GaOOH was enhanced by coating thin metal oxide ͑SnO 2 , rutile TiO 2 , anatase TiO 2 , and MgO͒ underlayers on quartz glass substrates, thereby resulting in the formation of uniform films. Transparent ␤-Ga 2 O 3 films were obtained by heat-treatments at higher temperatures. Upon excitation by ultraviolet light ͑250 nm͒, the ␤-Ga 2 O 3 films exhibited visible green luminescence.

Luminescence of Cr3+ ions associated with surpassing the green-emissive defect centers in β-Ga2O3

“…A filter, which eliminated light having wavelengths o350 nm, was used to remove a second-order peak of the excitation UV light. [17]. No significant change was observed in the XRD patterns of the Cr 3+ -doped b-Ga 2 O 3 samples prepared in the present study.…”

“…Fortunately, we have recently succeeded in fabricating transparent and green luminescent b-Ga 2 O 3 films through a chemical solution deposition of GaOOH and subsequent heat treatments. Details of the experimental procedures have already been reported elsewhere [17]. To prepare Cr…”

Well Crystallized α‐GaOOH Nanocrystals Synthesized through Hydrothermal Routes and Their Properties

“…A one-pot green synthesis technique was developed to prepare GaOOH nanorods through the hydrothermal reaction of nanocrystalline Ga 2 O 3 powders and distilled water at 200 ℃ without the use of any extra template or surfactant. 8 Fujihara's group 9 prepared GaOOH particles and films on a large scale from a simple aquous gallium nitrate solution. Ristić et al 10 obtained nanosized α-GaOOH particles by the addition of TMAH to the solution of gallium(III)-isopropoxide dissolved in 2-propanol.…”

Large‐scale synthesis of submicron gallium oxide hydrate rods and their optical and electrochemical properties

“…GaOOH nanoplatelets were synthesized by a hydrothermal process involving Ga(NO 3 ) 3 ·H 2 O·NaN 3 solutions [7]. Nanoscale or submicron GaOOH rods have been synthesized by different methods, such as ball-milled GaN powders [8], hydrothermal treatment of containing Ga starting materials by the addition of different surfactants [9][10][11][12]. However, surfactants are often required in order to generate GaOOH structures with submicron or nanoscale size which will cause higher cost and a more complicated purification procedure.…”