Search

We discuss several recent advances in the development of methodologies and techniques used to structurally and morphologically engineer chalcogenide (ChG) materials. We introduce two ChG patterning techniques both offering spatial resolution beyond the classical single-photon diffraction limit: multiphoton lithography and thermal scanning probe lithography (TSPL). The former was applied to produce nanoscale modifications in thermally deposited As2S3, and we realized gradient refractive index (GRIN) effective medium lens fabrication in multilayer As2S3-As2Se3 films with features as small as 120 nm using this approach. The GRIN lens was shown to be optically functional. ChG Ge-Sb-Se-Te (GSST) material was also explored for its potential as a phase-change material (PCM). We demonstrated nanoscale feature patterning using TSPL in PCMs with critical dimensions below 100 nm. In addition, new patterning methods, we also report solution processing of GSST PCMs as an alternative route for ChG film deposition. These new material processing and structuring techniques will offer new pathways for creating functional planar optical and photonic devices.

Transparent optical ZnO–Bi2O3–B2O3 (ZBB) glass-ceramics were created by the melt quenching technique. In this work, a melt of the glass containing stoichiometric ratios of Zn/Bi/B and As was studied. Differential scanning calorimeter (DSC) measurements was used to measure the thermal behavior. VIS/NIR transmission measurements were used to determine the transmission window. X-ray diffraction (XRD) was used to determine crystal phase. In this study, we explore new techniques and report a detailed study of in-situ XRD of the ZBB composition in order to correlate nucleation temperature, heat treatment temperature, and heat treatment duration with induced crystal phase.

Transparent optical glass-ceramics consisting of nanocrystals have the potential for use as optical devices such as waveguides, microlenses, and photonic crystals. ZnO–Bi2O3–B2O3 based glass ceramics were prepared via a melt quenching technique to assess parent glass and post-processed property evolution. Here, three large scale melts and six small test melts of the glass were melted at and around the 33.3 ZnO-33.3 Bi2O3- 33.3 B2O3 molar composition; some were also doped with small quantities of As2O3 for redox control or with LiNO3 as a nucleating agent. The physical and chemical properties including thermal behavior, transmission, elemental, and index of refraction of these melts were compared to assess their suitability as optical glasses and glass ceramics. Heat treatments were used to create transparent ZnO–Bi2O3–B2O3 glass ceramics containing BiB3O6 and Bi2ZnB2O7 nanocrystals. We correlate nucleation temperature, heat treatment temperature, and heat treatment duration with induced crystal phase formation. In addition to BiB3O6 and Bi2ZnB2O7 nanocrystals, ZnO was found to grow on the surface of some compositions. Compositional optimization and heat treatment procedures were developed to encourage volume crystallization while mitigating unwanted surface crystal growth. Laser-induced crystallization pads and lines were patterned in the glass to compare with and assess post-heat treatment phase and structure modification.

Transparent ZnO–Bi2O3–B2O3 (ZBB) glasses were prepared using the melt quench technique. Various compositions of the glass containing stoichiometric ratios of Zn/Bi/B as well as some including As2O3 for redox control and LiNO3 for use as nucleation species, were studied. ZBB glass-ceramics containing nanocrystallites have a potential for use as low-cost UV-MWIR optical devices such as microlenses, waveguides, and photonic crystals. Our goal was to exploit crystal growth in the ZBB systems by heat treatment in order to obtain transparent glass-ceramics that contain homogenous volume crystallization. Thermal behavior was studied using differential scanning calorimeter (DSC) measurements. Physical and optical characterizations included Raman spectroscopy to identify molecular connectivity, energy-dispersive X-ray spectroscopy (EDX) for elemental analysis, VIS/NIR transmission and reflection spectroscopy for optical bandgap and IR transmissivity, X-ray diffraction (XRD) to determine crystal phase, and transmission electron microscopy (TEM) combined with selected area electron diffraction (SAED) to quantify size, number density, and identification of nanometer sized secondary phases. Heat treatments were used to nucleate and grow BiB3O6 and Bi2ZnB2O7 nanocrystals in ZBB. We explored new compositions within the ZBB system and heat treatment techniques to assess the transformation of the amorphous glass phase into the crystalline phase. In-situ XRD and TEM imaging was employed to correlate nucleation temperature, heat treatment temperature, and heat treatment duration with induced crystal phase. BiB3O6, Bi2ZnB2O7, and ZnO was found to grow on the surface of some compositions. Compositions and heat treatment procedures were developed to facilitate volume crystallization and reduce unwanted surface crystallization.