Origin, secret, and application of the ideal phase‐change material GeSbTe

Abstract

Discovery of the GeSbTe phase‐change alloy in particular along the GeTe–Sb2Te3 tie‐line took place in the mid‐1980s. The amorphous alloys showed ideal properties, for example, high thermal stability at r.t. and laser‐induced rapid crystallization with large optical changes. Thereafter, GeSbTe was successively applied to various optical disks such as DVDs and BDs. Through DSC and XRD analyses, the appearance of the metastable phase having a NaCl‐type structure was observed over a wide compositional region. This was the “key” to realizing the ideal phase‐change properties. During this year, the role of the constituent elements of Ge and Sb became clear by RMC modeling using AXS data at SPring‐8, where the “nucleation dominant crystallization process” was well explained. magnified imageThe aspect of the latest Blu‐ray Disc (BD) product of Panasonic: GeSbTe phase‐change films are utilized in every recording layer. It is seen that the front‐side recording layers, L1 and L2, are highly transparent.

Structural transition and enhanced phase transition properties of Se doped Ge2Sb2Te5 alloys

“…However, these assumptions need a detailed study. The general understanding is that the metastable NaCl-like structure is important for crystallization process in phase change GST alloys19. The amorphous to hexagonal transition in the Se doped GST alloys also results in the reversible switching with comparable threshold voltages.…”

“…3(e) and the inset, a band centered at 147 cm −1 has been observed which originates from the amorphous GST. This band is believed to originate from SbTe 3 pyramids or edge sharing GeTe 4 tetrahedral vibrational modes111920. As the power of the laser decreases or filtering increases, the surface crystallization disappears.…”

Mixed‐Mode Electro‐Optical Operation of Ge2Sb2Te5 Nanoscale Crossbar Devices

“…[6] Exploiting both optical and electrical properties of phase-change materials simultaneously, and the possibility of modulating optical effects using electrical excitations, has only very recently opened up new application fields, such as low-power, nonvolatile, phase-change nano displays. [7][8][9] A deeper understanding of the relationship between the optical and electrical properties of phase-change materials, such as GST, is now urgently required to spur the development of new optoelectronic applications.…”

Exploring the applicability of amorphous films of system In-Sb-Te as phase change materials

“…Until now there are basically two classes of phase change materials in technological applications: the more widely used germanium antimony telluride [11] and indium antimony telluride based [12] materials. These materials have already been employed in optical discs such as CDs, DVDs and Blue-ray Discs since 1994 for Ge-Se-Te and 1997 for Ag-In-Sb-Te [13].…”