Woong-Chul Shin

Nonvolatile switching characteristics of laser-ablated Ge2Sb2Te5 nanoparticles for phase-change memory applications

Electrical characteristics of Ge2Sb2Te5 (GST) nanoparticles have been examined for a phase-change memory applications. The GST nanoparticles were generated by in situ pulsed laser ablation and their crystal structure formation was confirmed [H. R. Yoon et al., J. Non-Cryst. Solids 351, 3430 (2005)]. A stacked structure of the GST nanoparticles with 10nm of average diameter shows reversible nonvolatile switching characteristics between a high resistance state and a low resistance state as in the phase-change memory consisting of bulk GST thin film. Experimental results indicate that it is highly probable to test scaling issues of the phase-change memory with well-defined GST nanoparticles.

Critical Quenching Speed Determining Phase of Ge 2 Sb 2 Te 5 in Phase--Change Memory

During the phase-change process of Ge₂Sb₂Te ₅ in PRAM (phase-change random access memory), phase-change dynamics are strongly dependent on the quenching speed, i.e. the cooling speed of melted phase-change material. Here the paper reports the relation between quenching speed of programming pulse and phases of Ge ₂Sb₂Te₅ in phase-change memory in detail. The existence of critical quenching speed is identified, which determines amorphous and crystalline phases in melting followed by quenching operation

Experimental Setup for in Situ Investigation of Phase Changing Behavior in Phase-Change Random-Access Memory Medium by Microfocusing Nanosecond-Time-Resolved Ellipsometry

An ellipsometer with nanosecond time resolution has been proposed for the investigation of the phase change behavior of Ge2Sb2Te5 heated by electrical pulses of 20–100 ns in real time. This passive single-wavelength ellipsometer has a division-of-amplitude photopolarimeter (DOAP) configuration for polarization state detection to collect ellipsometric data in nanoseconds and consists of a microfocusing lens system to achieve a spot size of ~15 µm.