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Chemically cleaned GaP(001) surfaces in aqueous HF solutions are analyzed by using spectroscopic ellipsometry (SE), ex situ atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), wettability, and photoluminescence (PL) measurements. The wettability measurements have shown that the HF-cleaned surface is hydrophobic and the PL intensity has increased after etching in aqueous HF solutions.

Thermal annealing behaviors of GaAs(001) surfaces in dry N2 atmosphere have been studied by using spectroscopic ellipsometry (SE), optical microscopy, scanning electron microscopy, ex situ atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) techniques. The SE data indicate that thermal annealing at temperatures T below 500 °C causes no or a little influence on the surface morphology. Microscopic roughening starts to occur at T>600 °C and exhibits a saturated roughness value at ∼800 °C. AFM observation confirms the presence of a microscopically roughened surface overlayer after annealing at T∼600–750 °C and a macroscopically roughened overlayer at above 700 °C. The XPS data indicate the removal of As2O3 oxide after annealing at above 500 °C; however, the Ga2O3 oxide is always observed regardless of annealing temperature, although its peak intensity becomes remarkably large at T∼700 °C and small at T≥800 °C. Annealing at T=1000 °C leads to deliquesced sample surface. The native GaAs oxide is also found to act as a passivation film against annealing-induced PL degradation for T below ∼400 °C. [ABSTRACT FROM AUTHOR]

Thermal degradation of GaAs(001) surfaces has been studied using spectroscopic ellipsometry (SE), optical microscopy, ex situ atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) techniques. The SE data suggest that thermal annealing causes no or little influence on the surface native oxide layer at temperatures T≤500 °C. Microscopic roughening starts to occur on GaAs surface at T>500 °C, giving maximum AFM roughness (rms∼14 nm) at 540 °C, and then tends to smoothened at T>540 °C (rms∼2.5 nm at 580 °C). Macroscopically roughened surfaces are observed at T>500 °C, becoming more pronounced at higher annealing temperature. The Ga droplets are also observed at T≥600 °C that lead to catastrophically damaged surfaces and make SE measurement impossible. The XPS data indicate thinning of the native GaAs oxide in the limited temperature range 450

Chemically cleaned GaP(001) surfaces in 25% NH4OH solution have been studied using spectroscopic ellipsometry (SE), ex situ atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and wettability measurement techniques. The SE data clearly indicate that the solution causes removal of the native oxide film immediately upon immersing the sample. The SE data also indicate that when the native oxide film is completely etch removed, the resulting surface is still roughened. The estimated roughness thickness is ∼1.2 nm, in excellent agreement with the AFM rms value (∼1.2 nm). The XPS spectra confirm the removal of the native oxide from the GaP surface. The XPS data also suggest a thin oxide overlayer, ∼0.3 nm thick, on the etch-cleaned GaP surface. The wettability measurements indicate that the as-degreased surface is hydrophobic, while the NH4OH-cleaned surface is hydrophilic. This result is in direct contrast to those obtained from acid cleaned surfaces, which are usually hydrophobic. The origin of hydrophilicity may be singular and associated hydroxyl groups bonded on the GaP surface. [ABSTRACT FROM AUTHOR]

Thermal annealing behaviors of GaAs(001) surfaces in dry [N.sub.2] atmosphere are analyzed by using spectroscopic ellipsometry and photoluminescence (PL) techniques. The native GaAs oxide has acted as a passivation film against annealing-induced PL degradation for temperatures below 400 [degree]C.

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Copyright of Socio-Economic History / Shakai-Keizai Shigaku is the property of Socio-Economic History Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Socio-Economic History / Shakai-Keizai Shigaku is the property of Socio-Economic History Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)