Se-doped Ge 10 Sb 90 for highly reliable phase-change memory with low operation power
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Jeong Hee Park Process Development Team, Semiconductor R&D Division, Samsung Electronics Co., Ltd., Hwasung-City, Kyungki-Do 445-701, Korea (Received 17 February 2017; accepted 11 May 2017)
In this study, we propose a Se-incorporated Ge10Sb90 as a phase-change material for phasechange memory (PCM) with high reliability and low operation power. We investigated the effect of the Se concentration on the thermal and electrical properties of Se-doped Ge10Sb90 films by varying the Se concentration from 0 to 20 at.%. The crystallization temperature, crystallization activation energy, and maximum ten-year data retention temperature increased with the increasing Se, thus demonstrating the improved thermal stability of Se-doped Ge10Sb90 films with higher Se contents. More Se also increased the rate factor, band gap, threshold voltage, and load resistance. In addition, the crystallization speed, programming window, and resistances of both the amorphous and crystalline states increased with the increasing Se concentration. In contrast, the reset current decreased with the increasing Se concentration. These results demonstrate that Sedoped Ge10Sb90 is a highly promising material for PCM applications.
I. INTRODUCTION
As the portable electronic device, artificial intelligence, and IoT (Internet of Things) markets rapidly expand, so does the demand for nonvolatile memory. Flash memory technology, which is currently being used the most for nonvolatile memory applications, has faced physical limitations and downscaling issues. Therefore, many alternative nonvolatile memory technologies have been investigated such as phase-change RAM (PRAM), ferroelectric RAM (FeRAM), and resistance RAM (RRAM).1 Among next-generation nonvolatile memories, PRAM has been considered the most promising candidate due to its high scalability, cost-effectiveness, good compatibility with CMOS technologies, good endurance, and nonvolatility.2–8 The principle of PRAM operation relies on the difference between the electrical resistances of the amorphous and crystalline states, which represent the logic states ‘1’ and ‘0’, respectively.9 Currently, PRAM uses an electrical pulse to melt the phase-change material by joule heating for a RESET operation. Therefore, high power consumption is a major obstacle to developing high-density PRAM.10 However, Ge2Sb2Te5, which is the most common phase-change material used in PRAM, requires a high reset current. Because this material has a high melting temperature and low crystalline Contributing Editor: Don W. Shaw a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2017.221
resistivity,11,12 various strategies have been investigated to reduce the reset current, such as structural and material modifications. In the literature, Sb-rich alloys are considered to exhibit growth-dominated crystallization behavior, which could guarantee fast operation speed. Therefore, Sb-rich GeSb phase-change materials have been investigated, but their high reset current and low thermal stability are obstacles
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