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Transient grating experiments after optical band-gap pulsed illumination of amorphous a-As2Se3 thin films reveal the existence of a well defined transport process occurring on length- and time-scales of the order of micrometers and microseconds, respectively. We tentatively assign this fast process, corresponding to a mobility of 0.04 ± 0.005 cm2 V-1 s-1, to the diffusion of photoexcited charge carriers with microsecond lifetime. [ABSTRACT FROM AUTHOR]

Abstract: Investigations of light-induced volume expansion and surface pattern recording in amorphous chalcogenide layers and nano-layered structures (NLS) were extended to direct electron-beam recording on Se/As2S3 and Sb/As2S3 NLS. Light as well as e-beam induced bleaching occurs in all NLS, while volume expansion occurs only in chalcogenide–chalcogenide NLS and in homogeneous Se or As2S3 layers. Comparison of these two phenomena revealed the possible role of purely electronic and thermal processes in the interdiffusion and relief formation. The latter is supposed to be connected with radiation-induced defect creation, free volume increase under the increased fluidity conditions as well as with the possible additional influence of electrostatic forces and stress. [Copyright &y& Elsevier]

EXAFS analysis is performed on equiatomic GeSe and GeTe films to elucidate changes in the local atomic environments induced by crystallization. It reveals for both the films that the 4:2 configuration dominates in their as-deposited amorphous state. In their crystallized state, however, the 3:3 configuration prevails together with quasi-crystalline Ge clusters. The two chalcogenide films exhibit very similar characteristics such as hidden glass transition phenomenon during heating, dominance of the 3:3 configuration in their melt state, decreased optical bandgap upon crystallization, and reduced temperature dependence of electrical conduction accompanied with crystallization. These common properties are partly attributed to the structural changes identified through our EXAFS analysis. In particular, their previously reported non-ohmic current-voltage behaviors associated with the phase switching and the threshold switching are explained in terms of the local structural information. The special phase-change properties of the equiatomic GeSe film is explicated by its amorphous structure. [ABSTRACT FROM AUTHOR]

Abstract: The use of high resolution X-ray photoelectron spectroscopy to study chalcogenide glass thin films is analyzed. It is shown that the method is an effective tool to explore different chemical environments in the films and control chemical composition of the surface. Examples of the method applications such as kinetics study of induced silver dissolution in the thin films and investigation of oxidation on the surface of the thin film are presented. Limitations of the method are shown on the example of photoinduced structural transformations in chalcogenide glass thin films. [Copyright &y& Elsevier]

Abstract: The role of structure in the crystallization of Ge x Te100− x model system suitable for phase-change applications is established by determining the local environment of each constituent using EXAFS analysis. Across the compositional spectrum, both constituents satisfy the (8-N) rule in the amorphous state except that the Ge atoms are surrounded by ∼3.4 neighbors in the stoichiometric composition. The estimation of homopolar Ge–Ge and Te–Te bonds indicates that chemical order is preserved less for Ge than for Te atoms. The crystallized stoichiometric film consists of Ge clusters in addition to GeTe crystals, implying that the latter has appreciable concentration of Ge vacancies. [Copyright &y& Elsevier]

A chemical compositional heterogeneity develops on glass surfaces which have experienced rapid expansion/stretching – as during the press or press/blow process used in forming. A differential etching technique using HF and HBF4 is developed to demonstrate that such heterogeneities occur on the surface of commercial articles such as soda-lime silicate tumblers. Comparison with articles exposed to aggressive conditions in a well-characterized dishwasher reveals that similar corrosion patterns appear in both cases – as alternatively corroded/non-corroded regions arranged as striations running vertically along the tumbler. Analysis of these striae by imaging ellipsometry and interferometry indicates that they consist of ridges 50–150 nm high in relief with a width and repeat distance of 0.05–0.15 mm. This pattern is in qualitative agreement with a recent physical modeling study and suggests that the ridges arise from durable low alkali glass which is at the surface of the gob/parison before the press/blow and which has been striated by less durable, high alkali glass from the interior of the gob. Under corrosive conditions, the alkali-rich glass dissolves away to leave behind the durable ridge. [Copyright &y& Elsevier]