(Invited) Reaction of Aqueous Tetramethylammonium Sulfide on SiGe(100) 25% as a Function of pH

Autor:	Zhonghao Zhang, Anthony J. Muscat
Rok vydání:	2019
Předmět:	chemistry.chemical_classification Tetramethylammonium chemistry.chemical_compound Hydrolysis Aqueous solution X-ray photoelectron spectroscopy Sulfide chemistry Thermal desorption spectroscopy Covalent bond Inorganic chemistry Ion
Zdroj:	ECS Transactions. 92:47-56
ISSN:	1938-5862 1938-6737
DOI:	10.1149/09202.0047ecst
Popis:	Tetramethylammonium sulfide [(CH3)4N]2S dissociates in water yielding tetramethylammonium cation, which does not hydrolyze, and sulfide anion (S2-), which undergoes hydrolysis reactions forming HS-and H2S. The reaction of these three sources of S with the surface of SiGe(100) 25% was investigated by X-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD), and a speciation model as a function of pH. Lowering the pH of dilute aqueous TMAS increased the H2S concentration and the S coverage on the surface increased in tandem. Covalent Ge-S bonds formed, and the highest S/elemental Ge molar ratio was 0.66 at pH 2-3. The surface termination was mixed, that is H-SiGe-SH. H2S desorbed in a state with a peak temperature at about 550 K and GeS in a peak at about 600 K. The Ge atoms on the SiGe surface were preferentially oxidized in aqueous TMAS based on the O/Si and Ge123+/Ge molar ratios calculated from XPS data compared to control surfaces.
Databáze:	OpenAIRE
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