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Here stable colour changes induced by solid-state electrical switching of ultrathin films of a germanium-antimony-telluride alloy are demonstrated, adding to its established uses in data storage; possible applications include flexible and transparent displays. Smart thin-film colour displays Phase-change materials such as the alloy germanium antimony tellurium (GST) have found wide practical use in optical storage media such as rewritable DVDs. More recently, such materials are also being investigated as candidates for the next generation of electrically operated non-volatile memories. Harish Bhaskaran and colleagues now consider the possibility of combining both optical and electrical control in ultrathin phase-change films. They first demonstrate that stable colour changes can be achieved in thin films of GST and go on to showcase a range of possible applications such as flexible and transparent displays. The work offers a new type of optoelectronic framework, and while still at an early stage, it offers an intriguing promise for technological applications. The development of materials whose refractive index can be optically transformed as desired, such as chalcogenide-based phase-change materials, has revolutionized the media and data storage industries by providing inexpensive, high-speed, portable and reliable platforms able to store vast quantities of data. Phase-change materials switch between two solid states--amorphous and crystalline--in response to a stimulus, such as heat, with an associated change in the physical properties of the material, including optical absorption, electrical conductance and Young's modulus.sup.1,2,3,4,5. The initial applications of these materials (particularly the germanium antimony tellurium alloy Ge.sub.2Sb.sub.2Te.sub.5) exploited the reversible change in their optical properties in rewritable optical data storage technologies.sup.6,7. More recently, the change in their electrical conductivity has also been extensively studied in the development of non-volatile phase-change memories.sup.4,5. Here we show that by combining the optical and electronic property modulation of such materials, display and data visualization applications that go beyond data storage can be created. Using extremely thin phase-change materials and transparent conductors, we demonstrate electrically induced stable colour changes in both reflective and semi-transparent modes. Further, we show how a pixelated approach can be used in displays on both rigid and flexible films. This optoelectronic framework using low-dimensional phase-change materials has many likely applications, such as ultrafast, entirely solid-state displays with nanometre-scale pixels, semi-transparent 'smart' glasses, 'smart' contact lenses and artificial retina devices., Author(s): Peiman Hosseini [sup.1] , C. David Wright [sup.2] , Harish Bhaskaran [sup.1] Author Affiliations: (1) Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK, (2) College [...]

The development of materials whose refractive index can be optically transformed as desired, such as chalcogenide-based phase-change materials, has revolutionized the media and data storage industries by providing inexpensive, high-speed, [...]

A simple form of a SPICE macro model for a generic phase-change random access memory device is presented. The SPICE implementation is described using a series of increasing complex modeling blocks for dc to transient analysis.

The temperature distributions produced within semi-infinite and finite-thickness media heated by a moving laser beam with a Gaussian power-density profile are examined by use of a time-domain method. Convective losses, described by Newton's law of cooling, from the medium surfaces are included. Various medium absorption models are considered. The solutions are given as single integrals with respect to time of simple functions. The resulting expressions have been used to examine the role of surface losses in information storage and medical applications. The role of convective losses in optical recording systems is found to be insignificant. However, for medical applications, combined convective and evaporative surface losses represent an important surface-heat-loss mechanism.

Using a combination of diffraction analysis and the three-dimensional finite-difference time-domain technique, we investigate the behavior of the recording light distribution in a magnetically amplified magnetooptical storage recording system with the presence of the optical disk and both with and without the inclusion of a solid immersion lens. The relationship of the distribution with the incident polarization the air gap depth, and the disk structure is analyzed in detail. The results indicate that the distribution is strongly dependent upon each of these variables. Index Terms--Finite-difference time-domain (FDTD) methods, finite methods, magnetooptic films, magnetooptic recording.

Analytical expressions of the replay spectra from single- and multiple-recorded bits in patterned media have been derived. The expressions were extended to include position jitter noise and bit-size variations. Index Terms--Noise, patterned media, signal.

A GCA model is developed for the simulation of phase-transition processes in phase-change materials, such as GeSbTe alloys. The simulations have shown annealing cycles with nontrivial spatial and temporal variations in temperature.

A simplified analytical model of electrothermal writing by probe on a basic two layer phase change structure was developed and used to predict the required voltage levels for recording and the expected diameters of recorded crystalline and amorphous marks. It was found that thickness and electrical conductivity of the coating layer was important for determining the voltage as well as the shape of recorded bit.

A theoretical approach is presented to predict the spatial extent of the amorphous to crystalline transition region during the probe recording process on phase-change storage media. This approach shows that the amorphous to crystalline transition length can be minimized by reducing the thickness of the phase-change layer.