Understanding gaas Native Oxides By Correlating Three Liquid Contact Angle Analysis (3LCAA) and High Resolution Ion Beam Analysis (HR-IBA) to X-Ray Photoelectron Spectroscopy (XPS) as Function of Surface Processing
| Autor: | Timothy Karcher, Karen L. Kavanagh, S.D. Whaley, Aashi Gurijala, Nikhil Suresh, Saaketh Narayan, Jack M. Day, Robert Culbertson, Nicole Herbots, Amber A. Chow, Franscesca J. Ark, Shaurya Khanna, Sukesh Ram |
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| Rok vydání: | 2019 |
| Předmět: |
Ion beam analysis
Materials science Mechanical Engineering Analytical chemistry 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Surface energy 0104 chemical sciences Contact angle X-ray photoelectron spectroscopy Mechanics of Materials Etching (microfabrication) Monolayer General Materials Science Wafer 0210 nano-technology Stoichiometry |
| Zdroj: | MRS Advances. 4:2249-2263 |
| ISSN: | 2059-8521 |
| DOI: | 10.1557/adv.2019.320 |
| Popis: | Chemical bonding in native oxides of GaAs, before and after etching, is detected by X-Ray Photoelectron Spectroscopy (XPS). It is correlated with surface energy engineering (SEE), measured via Three Liquid Contact Angle Analysis (3LCAA), and oxygen coverage, measured by High Resolution Ion Beam Analysis (HR-IBA). Before etching, GaAs native oxides are found to be hydrophobic with an average surface energy, γT, of 33 ± 1 mJ/m2, as measured by 3LCAA. After dilute NH4OH etching, GaAs becomes highly hydrophilic and its surface energy, γT, increases by a factor 2 to a reproducible value of 66 ± 1 mJ/m2. Using HR-IBA, oxygen coverage on GaAs is found to decrease from 7.2 ± 0.5 monolayers (ML) to 3.6 ± 0.5 ML. The 1.17 ratio of Ga to As, measured by HR-IBA, remains constant after etching. XPS is used to measure oxidation of Ga and As, as well as surface stoichiometry on two locations of several GaAs(100) wafers before and after etching. The relative proportions of Ga and As are unaffected by adventitious carbon contamination. The 1.16 Ga:As ratio, measured by XPS, matches HR-IBA analysis. The proportions of oxidized Ga and As do not change significantly after etching. However, the initial ratio of As2O5 to As2O3, within the oxidized As, significantly decreases after etching from approximately 3:1 to 3:2. Absolute oxygen coverage, as a function of surface processing, is determined within 0.5 ML by HR-IBA. XPS offers insight into these modifications by detecting electronic states and phase composition changes of GaAs oxides. The changes in surface chemistry are correlated to changes in hydro-affinity and surface energies measured by 3LCAA. |
| Databáze: | OpenAIRE |
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