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Crystal Lattice Damage and Recovery of Rare-Earth implanted Wide Bandgap Oxides

Sarwar Mahwish, Ratajczak Renata, Ivanov Vitalii, Mishra Sushma, Turek Marcin, Wierzbicka Aleksandra, Woźniak Wojciech, Guziewicz Elżbieta

Advances in Science and Technology. Research Journal

2022

Vol. 16, no 5

147--154

Rare earth (RE) elements are important for the optical tuning of wide bandgap oxides (WBO) such as β-Ga2O3 or ZnO, because β-Ga2O3:RE or ZnO:RE show narrow emission lines in the visible, ultra-violet and infra-red region. Ion implantation is an attractive method to introduce dopant into the crystal lattice with an extraordinary control of the dopant ion composition and location, but it creates the lattice damage, which may render the dopant optically inactive. In this research work, we investigate the post-implantation crystal lattice damage of two matrices of wide-bandgap oxides, β-Ga2O3 and ZnO, implanted with rare-earth (RE) to a fluence of 5 x 10^14, 1 x 10^15 and 3 x 10^15 atoms/cm^2, and post-growth annealed in Ar and O2 atmosphere, respectively. The effect of implantation and annealing on both crystal lattices was investigated by channeling Rutherford backscattering spectrometry (RBS/C) technique. The level of crystal lattice damage caused by implantation with the same RE fluences in the case of β-Ga2O3 seems to be higher than in the case of ZnO. Low temperature photoluminescence was used to investigate the optical activation of RE in both matrices after performed annealing.

Gallium oxide buffer layers for gallium nitride epitaxy

Korbutowicz R, Wnek J, Panachida P, Serafinczuk J, Srnanek R

Optica Applicata

2013

Vol. 43, nr 1

73--79

Gallium nitride (GaN) is very attractive semiconductor material because of its unique properties. The serious matter is a lack of easy access to bulk crystals of GaN. Synthesized crystals are precious and rather small. For these reasons almost all device manufacturers and researchers apply alternative substrates for gallium nitride devices epitaxy and it causes that the technology is intricate. Alternative substrates need buffer layers – their technology is usually complex and expensive. We have proposed a simple method to avoid large costs: applying gallium oxide – monoclinic β-Ga2O3, as the buffer layer, which has structural properties quite good matched to GaN. As the substrates made from single crystal gallium oxide are still hardly available on the market, we have used hydride vapour phase epitaxy (HVPE) GaN epilayers as a starting material. It can be GaN layer under good quality – middle or low. The oxidation process converts top GaN to β-Ga2O3 layer which can release or absorb the strain. Applying such structure in another, second, epitaxy of GaN allows to obtain good quality epitaxial structures using HVPE technique.

Selective Hydrogenation of Crotonaldehyde over Gallia and Germania Supported Ruthenium Catalysts in a Gas Phase

Gebauer-Henke E., Rynkowski J.

Polish Journal of Chemistry

2008

Vol. 82, nr 1-2

25-31

Hydrogenation of crotonaldehyde in a gas phase at atmospheric pressure over Ru/support catalysts was studied. Ruthenium nitrozyloazotane Ru(NO)(NO3)3 and three supports: alfa-Ga2O3 (60.4 m2/g), beta-Ga2O3 (2.2 m2/g) and alfa-GeO2 (3.8 m2/g) were used for catalyst preparation with the nominal ruthenium content 5 wt. % and for the catalysts supported on alfa-Ga2O3 also 2 and 1 wt. %. The row of the catalytic performance of catalysts is as follows: 5 wt.%Ru/alfa-Ga2O3>5wt.%Ru/alfa-Ga2O3>5wt.%Ru/alfa-GeO2. The best catalyst, 5 wt. % Ru/alfa-Ga2O3, shows high selectivity to desired product-crotyl alcohol (above 85%) with the activity ca. 300 mi mol s–1 gRu