7440-38-2 Etching AlAs with HF for epitaxial lift-off applications

The epitaxial lift-off process allows the separation of a thin layer of III/V material from the substrate by selective etching of an intermediate AlAs layer with HF In a theory proposed for this process, it was assumed that for every mole of AIAs dissolved three moles of H2 gas are formed. In order to verify this assumption the reaction mechanism and stoichiometry were investigated in the present work. The solid, solution and gaseous reaction products of the etch process have been examined by a number of techniques, It was found that aluminum fluoride is formed, both in the solid form as well as in solution. Furthermore, instead of H2 arsine (AsH3) is formed in the etch process. Some oxygen-related arsenic compounds like AsO, AsOH, and AsO2 have also been detected with gas chromatography/mass spectroscopy. The presence of oxygen in the etching environment accelerates the etching process, while a total absence of oxygen resulted in the process coming to a premature halt. It is argued that, in the absence of oxygen, the etching surface is stabilized, possibly by the sparingly soluble A1F3 or by solid arsenic. https://www.lookchem.com/CASDataBase_7440-38-2.htm

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726-18-1 Electrophilic alkylations in neutral aqueous or alcoholic solutions

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102-82-9 Selective Synthesis of Secondary and Tertiary Amines by Reductive N-Alkylation of Nitriles and N-Alkylation of Amines and Ammonium Formate Catalyzed by Ruthenium Complex

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1023-17-2 Syntheses, structures, and catalytic activity in Friedel–Crafts acylations of substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes

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