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Over the past 30 years or more, chalcogenide phase-change materials and devices have generated much scientific and industrial interest, particularly as a platform for non-volatile optical and electronic storage devices. More recently, the combination of chalcogenide phase-change materials with photonic integrated circuits has begun to be enthusiastically explored, and among many proposals, the all-photonic phase-change memory brings the memristor-type device concept to the integrated photonic platform, opening up the route to new forms of unconventional (e.g., in-memory and neuromorphic) yet practicable optical computing. For any memory or computing device, fast switching speed and low switching energy are most attractive attributes, and approaches by which speed and energy efficiency can be improved are always desirable. For phase-change material-based devices, speed and energy consumption are both enhanced the smaller the volume of phase-change material that is required to be switched between its amorphous and crystalline phases. However, in conventional integrated photonic systems, the optical readout of nanometric-sized volumes of phase-change material is problematic. Plasmonics offers a way to bypass such limitations: plasmonic resonant structures are inherently capable of harnessing and focussing optical energy on sub-wavelength scales, far beyond the capabilities of conventional optical and photonic elements. In this work, we explore various approaches to combine the three building blocks of Si-photonics, resonant plasmonic structures, and phase-change materials to deliver plasmonically enhanced integrated phase-change photonic memory and computing devices and systems, underlining the inherent technical and theoretical challenges therein. [ABSTRACT FROM AUTHOR]

Presents two letters to a young writer, modeled on the influential "Letters to a Young Poet" by Rainer Maria Rilke. Notes the first letter situates itself when a young writer first turns toward poetry; and the second addresses the relationship between mentorship and the imagination, questioning the right of any writer to presume to guide the nascent mind of another. (RS)

The crystallization dynamics in the phase-change material Ge2Sb2Te5 is modelled using the more detailed Master equation method over a wide range of heating rates commensurate with published ultrafast calorimetry experiments. Through the attachment and detachment of monomers, the Master rate equation naturally traces nucleation and growth of crystallites with temperature history to calculate the transient distribution of cluster sizes in the material. Both the attachment and detachment rates in this theory are strong functions of viscosity, and thus, the value of viscosity and its dependence on temperature significantly affect the crystallization process. In this paper, we use the physically realistic Mauro-Yue-Ellison-Gupta-Allan viscosity model in the Master equation approach to study the role of the viscosity model parameters on the crystallization dynamics in Ge2Sb2Te5 under ramped annealing conditions with heating rates up to 4×104 K/s. Furthermore, due to the relatively low computational cost of the Master equation method compared to atomistic level computations, an iterative numerical approach was developed to fit theoretical Kissinger plots simulated with the Master equation system to experimental Kissinger plots from ultrafast calorimetry measurements at increasing heating rates. This provided a more rigorous method (incorporating both nucleation and growth processes) to extract the viscosity model parameters from the analysis of experimental data. The simulations and analysis revealed the strong coupling between the glass transition temperature and fragility index in the viscosity and crystallization models and highlighted the role of the dependence of the glass transition temperature on the heating rate for the accurate estimation of the fragility index of phase-change materials from the analysis of experimental measurements. [ABSTRACT FROM AUTHOR]

The three different modeling approaches are investigated to simulate the crystallization behavior of Ge2Sb2Te5 in optical and electrical phase-change memories. Different simulation-experiment comparisons to illustrate the capabilities of the model are discussed.

The problem of allocating increasingly limited funds appropriately in higher education is discussed in an introductory manner. The article describes the development of an allocation process that was developed and used in a college of education in making allocations of library/media funds to departments and program.