Presentation Information
[1603]Time-resolved optical effects in chalcogenide based phase-change materials
○Paul Fons1,2,3, Kirill Mitrofanov1, Muneaki Hase2,4, Alexander Kolobov1,3, Junji Tominaga1 (1.National Institute of Advanced Industrial Science & Technology, 2.RIKEN SPring-8 Center, 3.Japan Synchrotron Radiation Research Institute, 4.University of Tsukuba)
司会: 篠田弘造(東北大学)
Keywords:
phase-change material,ultra-fast optical excitation,free-electron laser,time-resolved structural measurements
The presence of optically-induced structural changes in chalcogenide semiconductors has a long history with the first reports of optical-induced photodarkening in vitreous chalcogenides appearing at the end of the 1960s. Subsequent reports also indicated the possibility of athermal photoamorphization of differing chalcogenides such as As50Se50 and Se suggesting that photosensitivity is a characteristic of some chalcogenide-based materials. These characteristics take on additional meaning when the materials used in nonvolatile optical storage and a new generation of nonvolatile electrical memory are considered as chalcogenide-based materials play important roles in each. In particular, the compound Ge2Te2Te5 is often considered as the prototypical phase-change memory alloy as it has enjoyed wide commercial success in the form of the nonvolatile optical storage media DVD-RAM and at the same time has served as the foundation of a new class of electrical storage phase-change random access memory which offers significant speed and lifetime improvements over charge-based flash storage. In phase-change materials information is stored in the form of structure and accessed by means of the very different electronic (reflectivity and transport properties) of the amorphous and crystalline phases. In this talk we will explore the effects of photo excitation on the structural and electronic properties of Ge2Te2Te5 alloys by means of time-resolved structural measurements using pump-probe experiments with both synchrotron radiation at SPring-8 and the free-electron laser facility SACLA. Based upon data collected from these time-resolved experiments, structural and property changes induced in bonding and local structure by laser-based excitation will be discussed.