am5b00083_si_001.pdf (1.85 MB)
Ti–Sb–Te Alloy: A Candidate for Fast and Long-Life Phase-Change Memory
journal contribution
posted on 2015-04-15, 00:00 authored by Mengjiao Xia, Min Zhu, Yuchan Wang, Zhitang Song, Feng Rao, Liangcai Wu, Yan Cheng, Sannian SongPhase-change memory (PCM) has great
potential for numerous attractive applications on the premise of its
high-device performances, which still need to be improved by employing
a material with good overall phase-change properties. In respect to
fast speed and high endurance, the Ti–Sb–Te alloy seems
to be a promising candidate. Here, Ti-doped Sb2Te3 (TST) materials with different Ti concentrations have been systematically
studied with the goal of finding the most suitable composition for
PCM applications. The thermal stability of TST is improved dramatically
with increasing Ti content. The small density change of T0.32Sb2Te3 (2.24%), further reduced to 1.37% for
T0.56Sb2Te3, would greatly avoid
the voids generated at phase-change layer/electrode interface in a
PCM device. Meanwhile, the exponentially diminished grain size (from
∼200 nm to ∼12 nm), resulting from doping more and more
Ti, enhances the adhesion between phase-change film and substrate.
Tests of TST-based PCM cells have demonstrated a fast switching rate
of ∼10 ns. Furthermore, because of the lower thermal conductivities
of TST materials, compared with Sb2Te3-based
PCM cells, T0.32Sb2Te3-based ones
exhibit lower required pulse voltages for Reset operation, which
largely decreases by ∼50% for T0.43Sb2Te3-based ones. Nevertheless, the operation voltages for
T0.56Sb2Te3-based cells dramatically
increase, which may be due to the phase separation after doping excessive
Ti. Finally, considering the decreased resistance ratio, TixSb2Te3 alloy with x around 0.43 is proved to be a highly promising candidate for fast
and long-life PCM applications.