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Investigation Of SnTe-Ge2 Sb 2 Te5 And Bi2 Te3 Based Phase-change Materials For Applications Of Phase Change Memory

Posted on:2013-02-28Degree:MasterType:Thesis
Country:ChinaCandidate:J A XuFull Text:PDF
GTID:2218330362459868Subject:Electronics and Communications Engineering
Abstract/Summary:PDF Full Text Request
Phase-change memory as one of themost promising candidates for the next-generation non-volatile solid-statememory hasmany advantages, for example, non-volatility,high stability, high speed, low power consumption, low cost, andcompatibility with complementary metal–oxide semiconductor(CMOS) technology. Intense research e?orts have been made to study phase change materials which are at the heart of PCM devices. Chalcogenide materials such as Ge2Sb2Te5 have been widely used in electrical data storage. However, with a low crystallization temperature, Ge2Sb2Te5 is susceptible to the issue of thermal cross-talk by the proximity e?ect.The high reset current results in high power consumption for Ge2Sb2Te5-based PCM.The switching speed is also not satisfactory. These issues stimulate us to explore a novel material system in order to improve the storing media characteristics. Here we try to look for solutions in terms of development and optimization of novel phase-change materials and following works have been done:1:SnTe doped in Ge2Sb2Te5material is proposed to increase the phase change speed. Thereversible phase change can be achieved by a voltage pulse as short as 30ns. Laser induced crystallization speed is accelerated due to SnTe incorporation.SnTe plays a same role as Sn in accelerating phase change speed. Furthermore, the phase separation in Sn-Ge2Sb2Te5 is supposed to be inhibited in SnTe-Ge2Sb2Te5.2:We co-sputter(Ge1.8Te)1-x(Bi2Te3)x with the aim of making the improvement of crystallization speed by Bi and advancement of stability by Ge. The data retention temperature of (Ge1.8Te)0.8(Bi2Te3)0.2 film is 110°C indicating a good thermal stability. Phase-change memory (PCM) cells based on(Ge1.8Te)1-x(Bi2Te3)x(x=0.2,03,0.4) could switch in a shoter time(50 ns , 30 ns and 10 ns) than that of Ge2Sb2Te5 based cell (100 ns). The power consumptions ofcells based on(Ge1.8Te)1-x(Bi2Te3)x(x=0.2,03,0.4) were much lower than that of Ge2Sb2Te5.(Ge1.8Te)1-x(Bi2Te3)xmaterials show potential as the active materials in high speed and lower power consumption phase change data storage media.3:We doped nitrogen intoBi2Te3film. The doped N atoms suppress the grain growth. With the increase of N concentration, theamorphous and crystalline resistivities increase. The resistivity of Bi2Te3-N-4 is 107Ω.The crystallization temperature also increases after N doping. The crystallization temperature of Bi2Te3-N-x(x=2,3,4) are all higher than 150℃.R-V curves of the device have demonstrated that the resistance margin of devicewith Bi2Te3-N-x(x=3,4) films are higher than 2 order. In hence,Bi2Te3-N-x has typical storage featuresin phase change memory application.
Keywords/Search Tags:Phase change memory, fast speed phase change material, SnTe doping, nitrogen doping, SnTe-Ge2Sb2Te5, Ge-Bi-Te, Bi2Te3-N
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