Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 12: Poster I

HL 12.53: Poster

Monday, March 8, 2004, 16:30–19:00, Poster A

Influence of Bi doping upon the phase change characteristics of Ge₂Sb₂Te₅ — •Ke Wang, Daniel Wamwangi, and Matthias Wuttig — I. Physikalisches Institut IA, RWTH Aachen, 52056 Aachen

Ge₂Sb₂Te₅ is a material which is commonly used in rewritable optical data storage. In this recording technology, the Ge-Sb-Te based alloys have been successfully developed as commercial products for PD and DVD-RAM applications due to their relatively short erasing time (30 100ns for Ge-Sb-Te). To ensure the future success of phase change recording the data transfer rate needs to be improved further. To achieve this goal faster materials are required. To this end doping of Ge₂Sb₂Te₅ has been suggested. Here we report on the influence of Bi doping on the speed of recrystallization (erasing) process, which is the time limiting step in optical recording. These experiments were performed by using both a static tester and an atomic force microscope. The evolution of bit topography and optical reflectivity under the irradiation of the erasing laser with different pulse duration is presented. For this Bi doped Ge₂Sb₂Te₅ film, ultrafast erasing is demonstrated and a second amorphization phenomenon is found during the erasing process. This behavior is related to structural properties and the activation barrier for the structure transition in this material. Acknowledgement One of the authors (K. Wang) would like to thank the Alexander von Humboldt Foundation for the fellowship.