Characterization of RF magnetron sputtered Se-doped Ge2Sb2.3Te5 thin films
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1072-G05-07
Characterization of RF magnetron sputtered Se-doped Ge2Sb2.3Te5 thin films Tomas Wagner1, Jan Gutwirth1, Jiri Orava1, Jan Prikryl1, Petr Bezdicka2, Miroslav Bartos1, Milan Vlcek3, and Miloslav Frumar1 1 General and Inorganic Chemistry and Research Centre, University of Pardubice, Faculty of Chemical Technology, Legion's sq. 565, Pardubice, 53210, Czech Republic 2 Institute of Inorganic Chemistry, AS CR, v.v.i., Husinec - Rez u Prahy, 25068, Czech Republic 3 Joint Laboratory of Solid State Chemistry, IMC ASCR, v.v.i. and University of Pardubice, Studentska st. 84, Pardubice, 53210, Czech Republic ABSTRACT RF magnetron sputtering technique has been used to deposit new films potentially applicable in phase-change memories. Ge2Sb2Te5 seems to be promising material, but it is not clear whether it is optimum composition for such application. We studied different deposition conditions and deposition of films doped by excess of Sb and doped also by Se, which equally replaces Te atoms compare to Ge2Sb2Te5. The sputtering target composition for our study was Ge2Sb2.3Te4Se1. Sputtered films contained less Se than target. Deposited films were characterized as-deposited and after thermal treatment in temperature range 30 – 300 °C. INTRODUCTION Since Ovshinsky discovered a new order–disorder memory phenomenon in Te-based chalcogenide glass in 1968 [1], this kind of materials has attracted much interest due to their wide technical applications especially in phase-change data storage technology. Currently, chalcogenide materials were used massively for rewritable non-volatile data storage. They are widely applied as active layers of rewritable optical discs as well as they are under intensive research targeted to development for alternative memories (called Phase-Change RAM (PC-RAM) or Chalcogenide RAM (C-RAM)) to commercially successful semiconductor FLASH memories [2]. Both optical and electrical recording is based on reversible phase transformation between amorphous and crystalline phase [3-8] caused by laser/electrical pulses. Detection consists in reflectivity difference (optical memories) or electrical resistance difference (PC-RAM) of amorphous and crystalline state in case of phase change memories. Second phenomenon is electrically induced reversible dissolution and separation of metallic Ag and vice versa in system of Ag doped chalcogenide glass, denoted as Programmable Metallization Cell (PMC) Memory [9, 10, 11]. Dominant compositions of active materials for their application in phase change memories include pure and doped Sb-Te, Ge-Sb-Te or Ag-In-Sb-Te systems. The Ge2Sb2Te5 (GST) thin films are finding application in electronics for data storage media including future non-volatile memories [8, 9] and thermoelectric energy conversion [12]. GST can be synthesized as nanowires [13] and deposited as nano-films by various methods, by RF or DC magnetron sputtering [14], metal organic chemical vapor deposition [15], thermal evaporation [16], also by deposition from solutions [17], and by PLD of the GST bulk materi
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