Improved performances of Ge₂Sb₂Te₅based phase change memory by W doping

Abstract

W-doped Ge 2 Sb 2 Te 5 materials have been investigated for phase change memory applications. W 0.08 (Ge 2 Sb 2 Te 5 ) 0.92 phase change film exhibits a higher crystallization temperature (255 °C), better data retention of 10 years at 183 °C, and higher crystalline resistance compared with traditional Ge 2 Sb 2 Te 5 . The W x (Ge 2 Sb 2 Te 5 ) 1%x films crystallize into a stable face-centered cubic phase with uniform crystal grains. Phase-change memory device based on W 0.08 (Ge 2 Sb 2 Te 5 ) 0.92 shows short operation time (10 ns) and good endurance (6 ' 10 5 cycles). W x (Ge 2 Sb 2 Te 5 ) 1%x material is a promising candidate for phase-change memory applications that require good data retention and fast operation speed.

Temperature and concentration dependent crystallization behavior of Ge2Sb2Te5phase change films: tungsten doping effects

“…Based on the TEM images and the corresponding selected area electron diffraction (SAED) of GSTW lms, the W atoms can uniformly distribute in the crystalline structure. 16 The atom radius of W is 139 pm, which is similar to that of Te (140 pm) and Sb (145 pm) atoms. It is supposed that most of the W atoms may act as substitutional impurities in the crystal lattice of GST.…”

“…17 Compared with PRAM based on GST, Cheng et al proved a higher operation speed in a single PRAM cell based on GSTW (10 ns for W 0.08 (Ge 2 Sb 2 Te 5 ) 0.92 and 50 ns for GST) and that the cyclability is not decreased as a result of the W doping. 16 Moreover, when GSTW is applied in devices, contact with the W electrode is inevitable and will reduce the interface effect. However, the phase change mechanism of the W-doped GST system has not been presented to date.…”

Phase‐Change Superlattice Materials toward Low Power Consumption and High Density Data Storage: Microscopic Picture, Working Principles, and Optimization

“…Moreover, the endurance of the N‐doped superlattice can reach 10 8 cycles, which is better than 10 6 cycles of GST‐SL (Figure o). Since many elements (such as C, N, O, Si, Ag, W, Bi, Sn) have been demonstrated to improve the performance of conventional bulk GST, similar attempts in GST‐SL should be expected.…”

A zero density change phase change memory material: GeTe-O structural characteristics upon crystallisation

“…Secondly, as a general feature of phase change materials, there is a severe volume shrinkage (6.5%–9.6%910) and corresponding increase in mass density upon crystallisation, which applies considerable mechanical stresses in the PCM cells11, and consequently, causes resistance drift and void formation in the device that finally limits the cyclability of the memory cells. In order to address these issues, other elements including nitrogen12, oxygen13, silicon14, tin15, carbon6, and tungsten16 as well as oxides such as SiO 2 17and Ta 2 O 5 18have been incorporated into the Ge 2 Sb 2 Te 5 material, leading to a higher crystallisation temperature with longer retention times and a reduced residual stress with smaller density change during the phase transition1018.…”