Surface Of Chalcogenide Glass Research Articles

Antireflective structured surface of chalcogenide glass fabricated using glass to glass molding

Chalcogenide (ChG) glasses with micro-nano structure arrays are increasingly demanded in infrared optical systems owing to their excellent antireflective properties, and can be mass-produced by precision glass molding (PGM). Nickel-phosphorus (Ni–P) plated molds are commonly used in the PGM process, but the Ni atoms tend to react with the ChG glass at high temperatures. In this study, we propose a novel two-step PGM process. A Ni–P mold is used to transfer antireflective micro-nano structure array to silicate glass. Then the silicate glass, which has a higher glass transition temperature (Tg) than the ChG glass, is used as the mold to replicate the antireflective structured surface to the ChG glass. The results show that the ChG glass micro-nano structure array has high forming accuracy and favorable infrared optical transmission characteristics. The silicate glass is proved to be an appropriate mold material for the ChG glass molding process. This work provides a novel type of the PGM techniques for ChG glass materials.

Fabrication of chalcogenide microlens arrays by femtosecond laser writing and precision molding

In this study, convex microlens arrays (MLAs) on chalcogenide glass (ChG) surface were fabricated through femtosecond laser direct writing and precision molding. Femtosecond laser writing was first employed to induce regularly arranged damage craters on the surface of silica glass. Then, the surface of silica was etched with hydrofluoric acid to obtain a smooth concave MLA. Finally, the concave microlens of silica was replicated on the surface of ChG by precision molding to obtain ChG MLA. The resulting ChG MLA had a uniform structure, clear image, and good focusing effect. By optimising the parameters of laser direct writing and chemical etching, we produced 1600 rectangular and hexagonal microlenses from As2Se3.The optical performances of MLAs were demonstrated by their excellent imaging and focusing capabilities. The method applied provides an efficient way to prepare large-scale MLA masks and MLAs.

Surface plasticizing of chalcogenide glasses: a route for direct nanoimprint with multifunctional antireflective and highly hydrophobic structures.

Chalcogenide glasses are attractive materials for optical applications. However, these applications often require pattering of the surface with functional micro-/ nanostructures, which is challenging by traditional microfabrication. Here, we present a novel, robust, and scalable approach for the direct patterning of chalcogenide glasses, based on soft imprinting of a solvent-plasticized glass layer formed on the glass surface. We established a methodology for surfaces plasticizing, through tuning of its glass transition temperature by process conditions, without compromising on the chemical composition, structure, and optical properties of the plasticized layer. This control over the glass transition temperature allowed to imprint the surface of chalcogenide glass with features sized down to 20 nm, and achieve an unprecedented combination of full pattern transfer and complete maintenance of the shape of the imprinted substrate. We demonstrated two applications of our patterning approach: a diffraction grating, and a multifunctional pattern with both antireflective and highly hydrophobic water-repellent functionalities - a combination that has never been demonstrated for chalcogenide glasses. This work opens a new route for the nanofabrication of optical devices based on chalcogenide glasses and paves the way to numerous future applications for these important optical materials.

Direct surface patterning of amorphous chalcogenide layers with high- energy H+ and He+ ion beams

As (Ge)–S (Se) based amorphous bulk chalcogenide glasses and layers have been used for surface geometrical relief recording by 2 MeV energy H+ and He+ ion-beams. The formation of giant (height modulation from nanometers up to micrometers) geometrical reliefs (dots, lines), have been investigated. Efficiency of surface patterning was compared for selected compositions, type of ion beam and conductivity of substrates. Comparisons with optical and e-beam recording were made with aim to establish the details of relief formation mechanisms. The results show applicability of high-energy ion beams for in situ fabrication of planar optical elements on the surface of chalcogenide glasses (bulk samples or amorphous films).

Direct soft imprint of chalcogenide glasses

The authors explored an approach for nanostructuring of surfaces of chalcogenide glasses by direct soft nanoimprint lithography. The authors produced soft nanoimprint molds with microsized and nanosized relief features using polydimethylsiloxane. To enable the direct replication of the mold pattern on the surface of bulk chalcogenide glasses, the authors engineered a thermal imprint tool that prevents the substrate deformation using a physical confinement. The authors optimized the imprint process parameters to achieve an unprecedented full transfer micropattern onto a bulk chalcogenide glass. Furthermore, the authors explored pattern replication of nanosized structures by thermal imprint. This process paves the way for a facile and cost-effective fabrication of nanostructures on chalcogenide glasses and their numerous applications in optical and photonic devices.

Observations of fractal patterns induced on surface of chalcogenide glass

Properties of chalcogenide glasses were studied. After heat treatment, fractal patterns were found on surfaces of Ge23Se67Sb10 and Ge30Se60Sb10 glasses. According to box counting method, the fractal dimensions are determined as 1.58–1.61, which are similar to that of the fractal crystal GeSe2. By analysis, the main factors for the formation of the fractal patterns are the glass structure and the weak interface energy anisotropy. Comparing the fractal pattern with compact seaweed pattern in undercooled Co-Sn melt, the growth mechanism of the fractal pattern in glass is similar to that in undercooled melt, i.e. the larger undercooling leads to the weaker of the interfacial energy anisotropy, which leads to the formation of fractal structure.

Photoinduced formation of Ag nanoparticles on the surface of As2S3/Ag thin bilayer

In this article, we demonstrate the combined effect of photodoping and photoinduced-surface deposition in a bilayer of chalcogenide glass (ChG) and Ag as an alternative method to optically synthesize Ag nanoparticles (AgNP) on the surface of ChG. In our experiment, AgNP formation occurs through two distinct stages: In the first stage, Ag is transported through the As2S3 layer as Ag+ ions, and in the second stage Ag+ ions are photo-deposited as AgNP. The ex situ x-ray photoelectron spectroscopy measurements and AFM observations show photoinduced Ag mass transport and the formation of AgNP.

Antireflection-coating optical items made from materials for the IR range by creating porous microstructures on the surface

This paper discusses a method of obtaining a porous antireflection layer on the surface of chalcogenide glasses by ion–chemical etching, as a result of which a porous microstructure is created that reduces the reflectance from the surface to 0.1–0.2%.

Fine embossing of chalcogenide glasses: First time submicron definition of surface embossed features

Fine micro- and nano-structures were fabricated in the surface of chalcogenide glasses by hot embossing. A Perkin Elmer Thermomechanical Analyser (TMA 7) and an in-house designed and built vacuum pressing rig were employed for embossing and the process parameters of embossing were optimised empirically. The moulds used were a silicon-on-insulator (SOI) wafer presenting 300nm–2μm scale features and a silicon wafer containing 1–10μm wide and ∼10mm long channels. We report typical results of surface embossing four samples of bulk Ge15As15Se17Te53 glasses. The applied pressure ranged from ∼5 to 500kPa and the temperature was set to be 60–70°C higher than the glass transition temperature (Tg), as measured by differential thermal analysis. With the increase of pressure, and use of a vacuum environment, the quality of embossing structure has been improved. Under the optimum pressing conditions, 300nm feature scale structures were successfully replicated from the mould opening the possibility of using hot embossing to fabricate nano-photonic devices. Due to its relative simplicity, hot embossing offers the potential to produce photonic integrated circuits and components based on novel inorganic compound glasses at low-cost, high-volume, and for a wide wavelength range.

Nanostructured chalcogenide glasses

Studies on nanoscale structures of chalcogenide glasses are briefly reviewed, and a focus is given upon applications of scanning probe microscopy to chalcogenide glasses. Using the microscope, we can inspect and modify the surface of chalcogenide glasses with nanometer resolution.

The formation of a crystalline layer on the surface of chalcogenide glass under the influence of water

The influence of water on the heat-treatment on AsTeGe amorphous semiconductors was investigated. When a slab of a semiconductor is heat-treated at a temperature below the glass transition temperature, the existence of water in the ambient atmosphere produces a pronounced effect. The surface conductance after the heat treatment remains unchanged in vacuum or in dry air, but it is increased by three orders of magnitude in wet air or in boiling water for 90 min. This effect is attributed to a crystalline Te layer formed on the surface, which has been verified from reflection-electron-diffraction analysis.