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The crystalline–amorphous–crystalline transition process of an oxygen-tuned Sb phase-change material has been obtained by employing ab initio molecular dynamic calculations. By analyzing the local atomic arrangement and the electron structure of the SbO system, the intrinsic mechanism is explored to comprehend the material function: (1) ultrafast crystallization and difficulty in creating a glassy state of a pure Sb material might be caused by the resonance bonding of linear arrangement Sb atoms in the rhombohedral phase; (2) the impurity oxygen atoms break the medium and long-range linear arrangement of the Sb network by steric effects and change the electronic structure of these Sb atoms bonded to oxygen atoms, i.e., the obvious increase in electron localization and the great decrease in state distribution around the Fermi surface due to the high electronegativity of oxygen. These factors set an effective barrier for crystallization and improve the amorphous stability and, thus, data retention. The present research and scheme provide important insights into the engineering and manipulation of a phase-change material through first-principles calculations toward non-volatile phase change memory. [ABSTRACT FROM AUTHOR]

Operation speed, data retention, thickness variation, and resistance drift are main shortages for conventional Ge2Sb2Te5 based phase change memory (PCM). In this Letter, we propose a type of ultrathin amorphous carbon (a-C)/Sb2Te multilayer nanostructures with semiconductor process compatibility, which has high speed and excellent reliability in terms of data retention (131 °C for 10-year), thickness variation (1.52%), and resistance drift (0.0095). The PCM devices based on [a-C (1 nm)/Sb2Te (7 nm)]5 multilayer nanostructures exhibit a fast operation speed of 5 ns. The SET/RESET resistance ratio remains constant over 105 cycles by more than two orders of magnitude. The excellent performance of a-C/Sb2Te multilayer nanostructures makes it a promising storage medium to expand the applications of PCM, such as automotive electronics. [ABSTRACT FROM AUTHOR]

Balancing operation speed and thermal stability is a big challenge in phase change memory (PCM). In this work, a carbon (C) and chromium (Cr) co-doped Sb2Te strategy has been proposed for achieving high operation speed and high stability in PCM applications. In general, doping with the appropriate Cr element is beneficial to improve thermal stability, but it will sacrifice its operation speed. C-doping can enhance thermal stability and retain its fast phase transition properties due to the carbon elements tend to form agglomerates in the host that ameliorate disorder of the amorphous phase without loss of the phase transition rate. Intriguingly, the as-prepared C1.19Cr0.23Sb2Te material exhibits good data retention (T10-year @ 155.0 °C) and low-volume change rate (1.8%), as well as fast switching speed (4 ns) and good endurance (>1 × 105 cycles). This research indicates that C and Cr co-doping is an effective method to achieve excellent stability of phase-change materials without sacrificing the phase-transition rate of Sb2Te materials. [ABSTRACT FROM AUTHOR]

Phase change memory (PCM), due to the advantages in capacity and endurance, has the opportunity to become the next generation of general−purpose memory. However, operation speed and data retention are still bottlenecks for PCM development. The most direct way to solve this problem is to find a material with high speed and good thermal stability. In this paper, platinum doping is proposed to improve performance. The 10-year data retention temperature of the doped material is up to 104 °C; the device achieves an operation speed of 6 ns and more than 3 × 105 operation cycles. An excellent performance was derived from the reduced grain size (10 nm) and the smaller density change rate (4.76%), which are less than those of Ge2Sb2Te5 (GST) and Sb2Te3. Hence, platinum doping is an effective approach to improve the performance of PCM and provide both good thermal stability and high operation speed. [ABSTRACT FROM AUTHOR]

While alloy design has practically shown an efficient strategy to mediate two seemingly conflicted performances of writing speed and data retention in phase-change memory, the detailed kinetic pathway of alloy-tuned crystallization is still unclear. Here, we propose hierarchical melt and coordinate bond strategies to solve them, where the former stabilizes a medium-range crystal-like region and the latter provides a rule to stabilize amorphous. The Er0.52Sb2Te3 compound we designed achieves writing speed of 3.2 ns and ten-year data retention of 161 °C. We provide a direct atomic-level evidence that two neighbor Er atoms stabilize a medium-range crystal-like region, acting as a precursor to accelerate crystallization; meanwhile, the stabilized amorphous originates from the formation of coordinate bonds by sharing lone-pair electrons of chalcogenide atoms with the empty 5d orbitals of Er atoms. The two rules pave the way for the development of storage-class memory with comprehensive performance to achieve next technological node. In phase-change memory, writing speed and data retention are two seemingly conflicting performances. Here the authors report hierarchical melt and coordinate bond strategies to stabilize a medium-range crystal-like region and amorphous region, respectively. [ABSTRACT FROM AUTHOR]

The era of information explosion is coming and information need to be continuously stored and randomly accessed over long-term periods, which constitute an insurmountable challenge for existing data centers. At present, computing devices use the von Neumann architecture with separate computing and memory units, which exposes the shortcomings of "memory bottleneck". Nonvolatile memristor can realize data storage and in-memory computing at the same time and promises to overcome this bottleneck. Phase-change random access memory (PCRAM) is called one of the best solutions for next generation non-volatile memory. Due to its high speed, good data retention, high density, low power consumption, PCRAM has the broad commercial prospects in the in-memory computing application. In this review, the research progress of phase-change materials and device structures for PCRAM, as well as the most critical performances for a universal memory, such as speed, capacity, and power consumption, are reviewed. By comparing the advantages and disadvantages of phase-change optical disk and PCRAM, a new concept of optoelectronic hybrid storage based on phase-change material is proposed. Furthermore, its feasibility to replace existing memory technologies as a universal memory is also discussed as well. [ABSTRACT FROM AUTHOR]

Al-doped Ge55Te45 materials are proposed for phase change memory application. Al incorporated in Ge55Te45 increases the crystallization temperature, band gap and 10-year data retention significantly. However, the crystallization speed of the Al-doped Ge55Te45 material will be lowered by excessive Al doping. The crystallization of the Al-doped Ge55Te45 film is observed to be growth-dominant, beginning with a random formation of spherical crystalline clusters. The 10-year data retention and crystallization speed of Al1Ge55Te45 are 117 °C and 5 ns, respectively, which makes the Al1Ge55Te45 a promising candidate for high speed PCM application. The 10-year data retention of 132 °C and good cyclic ability of ∼2 × 103 cycles of the Al2Ge55Te45 based PCM have shown its application potential in automotive fields. [ABSTRACT FROM AUTHOR]

Transition metal elements doping can greatly improve the usability of Sb–Te for phase change memory. In this paper, we focused on the thermal stability of transition vanadium (V)-doped Sb2Te (VSb2Te) films with different V concentration which were prepared by co-sputtering. The effects of V doping on the crystallization and microstructure properties of Sb2Te were studied by temperature-dependent resistance measurements, in-situ heating TEM and HRTEM observation, respectively. With increasing V content, the crystallization is inhibited and the data retention is obviously enhanced, and the grain size shrinks significantly. Ab initio molecular dynamics simulation was used to explain the mechanism of the improved thermal stability and the results show that the diffusion of Sb and Te atoms are suppressed by doped V, which may account for the high thermal stability of VSb2Te. [ABSTRACT FROM AUTHOR]

Abstract: Phase‐change memory is one of the most attractive solutions for embedded applications, thanks to the low cost of integration with current manufacturing processes and the good scaling behavior. Despite intensive research efforts that are devoted to the modification of Ge2Sb2Te5 (GST) phase‐change material, the obtained improvements are still unsatisfactory for high‐performance applications. In this paper, SiC‐modification is first introduced to enhance the amorphous stability of GST without sacrificing its transition speed. Several enhancements can be demonstrated, including better thermal stability (10‐year data retention above 120 °C), lower RESET voltage (about 3.0 V at 20 ns pulse width), reduced volume change (smaller than 3.0%), and expected operation cycles (more than 1.0 × 105). According to the findings, the local bonding nature of Ge/Te atoms can be tuned by C/Si dopants through forming CGe and SiTe bonds. Apart from strengthening the atomic binding network for desirable data retention, the element interdiffusion is also effectively controlled and suppressed. Together with finer grains, smaller density change, and more uniform morphology, the modified structure transition finally contributes to the reduced switching voltage and long‐term endurance. Hence, it is envisaged that SiC‐doped GST with such advantages will give a competitive option for high‐density and high‐performance embedded memory. [ABSTRACT FROM AUTHOR]

Phase change behavior in Al(SnSe) (x = 0.003, 0.010, 0.023) films were investigated by utilizing in situ resistance measurements. It is found that the crystallization temperatures and resistances increase with increasing of Al content. The analysis of X-ray diffraction indicates that the grain size decreases and the crystallization is suppressed by more Al doping. Al(SnSe) has an excellent thermal stability with the crystallization activation energy of 3.79 eV and the failure time is longer than that of GeSbTe film. The crystallization speed of Al(SnSe)film is faster than that of GST. The phase transition kinetics of Al(SnSe)films were investigated. The obtained values of Avrami indexes indicate that a one dimensional growth-dominated mechanism is responsible for the amorphous-crystalline transformation of Al(SnSe)film. We conclude that Al(SnSe) film is a good candidate for phase-change random-access memory applications with good thermal stability and high switching speed. [ABSTRACT FROM AUTHOR]

The multi-step resistance behavior was observed in the Ge2Sb2Te5/GeTe bistratal stacked films investigated by utilizing in situ temperature-dependent film resistance measurements. The [Ge2Sb2Te5(30 nm)/GeTe (70 nm)] stacked films had a larger resistance difference among different resistance states. The data retention temperatures for 10 years of amorphous and intermediate states of [Ge2Sb2Te5(30 nm)/GeTe (70 nm)] films were estimated to be 126°C and 166°C, respectively. X-Ray Diffractomer revealed the changes of phase structure in Ge2Sb2Te5/GeTe bistratal stacked films with different annealing temperature. Theoretical simulation of the temperature distribution of the PCM cell with bistratal films was used to examine the multi-step switching mechanism. [ABSTRACT FROM AUTHOR]

The thermal stability of amorphous Sb2Te film can be significantly improved by the addition of Cu. CuSb4Te2 alloy is considered to be a potential candidate for phase change random access memory (PCRAM), as evidenced by a higher crystallization temperature, a better data retention ability, and a faster switching speed in comparison with those of Ge2Sb2Te5. A reversible switching between set and reset states can be realized by an electric pulse as short as 7 ns for CuSb4Te2-based PCRAM cell. In addition, CuSb4Te2 shows endurance up to 1.5 × 105 cycles with a resistance ratio of about two orders of magnitude. [ABSTRACT FROM AUTHOR]

With a high crystallization temperature of 211 °C, Ti10Sb60Te30 phase change material exhibits a data retention of 10-yr at 137 °C, which is much better than that of usual Ge2Sb2Te5. No other phase is formed in Ti10Sb60Te30 film except hexagonal Sb2Te phase. For Ti10Sb60Te30-based phase change memory cell, as short as 6 ns electric pulse can fulfill the Set operation, demonstrating an extremely rapid crystallization speed of Ti10Sb60Te30. The programming cycles can reach 2.2 × 104 with very short Set/Reset pulses of 100 ns/50 ns. [ABSTRACT FROM AUTHOR]

Focusing on meeting the requirements for embedded applications of faster switching and sensing, lower‐power consumption, higher reliability, longer cycling endurance, and higher temperature retention, a lot of progress in the phase change memory (PCM) field has been made, including materials improvement, process optimization, new circuits design, and better operation algorithms. Finally, a 128 MB embedded PCM chip has been demonstrated in 40 nm node. Using carbon‐doped Ge2Sb2Te5 phase change material and 3 nm thick heating bottom electrode contact (BEC) with nitride coating, a resistance ratio of more than two orders of magnitude has been achieved in Reset and Set states. Combined with the parasitic matched sensing circuit, optimized ramp‐down SET pulses, adaptive pre‐read and write‐verify methods, and automatic configure and test procedures, the chip exhibits excellent data retention and endurance characteristics with minimum program time of 200 ns, and the Reset/Set resistance ratio becomes even larger after 260 °C soldering test. The estimated data retention time is 10 years at 128 °C, and in a 128 MB full integrated chip the endurance over 109 cycles is achieved. It is confirmed that this PCM technology is suitable for embedded applications, especially for those with crucial requirements of high access speed, high thermal stability, and cycling endurance. This review summarizes the authors' main progress in phase change memory (PCM) technology and presents a PCM device based on carbon‐doped Ge2Sb2Te5 (CGST) as a 128 MB chip, demonstrating the following key properties: minimum Read/Write time of 10 ns/200 ns, over 1011 cycles endurance of the TiN blade bottom electrode contact with nitride coating, Reset/Set ratio over two orders of magnitude, 10‐year 128 °C data retention, and over 109 cycles endurance of the device. It has great potential for embedded applications. [ABSTRACT FROM AUTHOR]

Compared with Ge2Sb2Te5, Ge0.61Sb2Te has higher crystallization temperature (∼200.5 °C), larger crystallization activation energy (∼3.28 eV), and better data retention (∼120.8 °C for 10 yr). The switching between amorphous and crystalline state could be triggered by the electric pulse of as short as 10 ns. With the resistance ratio of two orders of magnitude, the endurance test was up to 106 cycles. Ge0.61Sb2Te material is a promising candidate for the trade-off between programming speed and data retention. [ABSTRACT FROM AUTHOR]

W-Sb-Te phase-change material has been proposed to improve the performance of phase-change memory (PCM). Crystallization temperature, crystalline resistance, and 10-year data retention of Sb2Te increase markedly by W doping. The Wx(Sb2Te)1-x films crystallize quickly into a stable hexagonal phase with W uniformly distributing in the crystal lattice, which ensures faster SET speed and better operation stability for the application in practical device. PCM device based on W0.07(Sb2Te)0.93 shows ultrafast SET operation (6 ns) and good endurance (1.8 × 105 cycles). W-Sb-Te material is a promising candidate for the trade-off between programming speed and data retention. [ABSTRACT FROM AUTHOR]

In this paper, Sb 52 Se 36 Te 12 is proposed for its good data retention and extremely rapid crystallization speed. Compared with usual Ge 2 Sb 2 Te 5 , Sb 52 Se 36 Te 12 exhibits a higher crystallization temperature of 196 ○ C, a better thermal stability, indicating a brilliant performance for data retention of 10 years at 121 ○ C, and a much faster switching speed, which is demonstrated by an electric pulse as short as 8 ns that can fulfil the set operation. Thus, Sb 52 Se 36 Te 12 could be expected to have a wide application in the fields of phase change memory with rapid crystallization speed and high-temperature data retention. [ABSTRACT FROM AUTHOR]

In the research on phase change materials, it has been found that there is still much potential for progress in the three areas of speed, thermal stability, and data retention. In this study, we propose Zn as a doping element to improve the properties of Sb 2 Te 3 phase change materials in order to overcome the contradiction between thermal stability and fast crystallization rate of Sb–Te alloys. The device based on Zn 37 (Sb 2 Te 3) 63 alloy shows that it can achieve the higher crystallization temperature (224 °C), faster switching speed (6 ns) and smaller operating voltage (1.2 V) than Ge 2 Sb 2 Te 5. And the ten years of data retention of Zn 37 (Sb 2 Te 3) 63 film test reached 132 °C, to meet the requirements of automotive and electronic products. By investigating the microstructure of the material, it was found that due to the effective inhibition of grain growth by Zn doping, the power consumption of the device was reduced and the durability was improved to allow 2.5 × 105 cycles. According to the thermal and electrical properties above, the Zn 37 (Sb 2 Te 3) 63 alloy has a great potential for development in phase-change memory applications. • Zn 37 (Sb 2 Te 3) 63 crystallizes at 224 °C and has a 10-year data retention of 132 °C. They are significantly higher than the crystallization temperature (150 °C) and ten-year data retention (85.8 °C) of Ge 2 Sb 2 Te 5. It has good thermal stability and meets the high-temperature requirements of automobiles and electronic products. • The effect of Zn doping on the grain size and phase transition process was investigated by XRD, TEM, XPS, etc. • The grain structure and elemental distribution of the annealed Zn 37 (Sb 2 Te 3) 63 films were analyzed by EDS, and it was observed that the Zn element doping formed ZnTe distributed around Sb 2 Te 3 , which suppressed the grain growth. • The rate of change in density of Zn 37 (Sb 2 Te 3) 63 before and after the phase transition is 5.58 %, which is lower than that of Ge 2 Sb 2 Te 5 (6.5 %) by XRR test. • Phase change materials based on Zn 37 (Sb 2 Te 3) 63 alloy present high operation speed (6 ns), and great durability (2.5 × 105 cycles). [ABSTRACT FROM AUTHOR]

In this paper, Ga0.6Ge2.8Sb2.6Te4 film was investigated for long data retention phase change memory application. Compared with Ge2Sb2Te5, Ga0.6Ge2.8Sb2.6Te4 film has higher crystallization temperatures (~240°C) and larger crystallization activation energy (~2.9eV), which lead to a higher temperature (~135°C) for ten year data retention. The reversible phase change can be realized by a 100-ns width electric pulse. Ga0.6Ge2.8Sb2.6Te4 based cell shows good endurance up to 1.05×105 SET–RESET cycles during endurance test. [ABSTRACT FROM AUTHOR]

• The Se dopant into Ge-Sb-Te ternary system increases its thermal stability. • Modifying the content of Ge enhances the temperature endurance of GSST alloy. • Increased thermal stability was reflected by changed crystallization process. The GSST (Ge-Sb-Se-Te) alloy has been investigated to be a competitive material choice for high density phase-change memory with robust data retention by introducing the doped Se and the excess Ge in Ge-Sb-Te ternary system. The Se dopants are found to increase the crystallization temperature and reduce the grain size. And the excess Ge atoms play a vital role in promoting the thermal stability of doped alloy. The reversible memory switching capability evidences that the GSST alloy is a potential reliable phase-change material in storage application for automobile systems. [ABSTRACT FROM AUTHOR]

The superlattice-like (SLL) GaSb/Ge 2 Te multilayer thin films were proposed for multilevel ultralong-retention phase-change memory (PCM). Multiple resistance states can be achieved by tuning the thickness ratio between GaSb and Ge 2 Te layers. The intermediate resistance state could be maintained at a large temperature gap over a wide range from 270 to 355 °C, which guarantee the substantial reliability of the multilevel storage. The high crystallization temperature and 10-years data-retention temperature indicate the high thermal stability of the GaSb/Ge 2 Te films. After crystallization, the density of the GaSb/Ge 2 Te multilayer thin films increased slightly. It is in favor of the high reliability for the multilevel PCM. The two crystallization processes and three resistance states support a multilevel storage in the GaSb/Ge 2 Te-based test cell. The multiple resistance states originate from the localization of the electronic states, which result from the disorder as a result of doping element migrating from neighbor layer. The minimum energy necessary for RESET operation of GaSb/Ge 2 Te (3.7 × 10 − 11 J) is lower than that of Ge 2 Sb 2 Te 5 (8.1 × 10 − 10 J) cell. GaSb/Ge 2 Te-based cell exhibited lower power consumption, high thermal stability and fast switching speed, suggesting GaSb/Ge 2 Te being one of the potential materials for multilevel PCM. [ABSTRACT FROM AUTHOR]

Phase-change memory is regard as one of the most promising candidates for the next-generation non-volatile memory. In this work, we proposed a Sb 7 Te 3 /ZnSb multilayer thin films to improve the thermal stability of Sb-rich Sb 3 Te 7 . The sheet resistance ratio between amorphous and crystalline states reached up to 4 orders of magnitude. With regard to the thermal stability, the calculated temperature for 10-year data retention is about 127 °C. The threshold current and threshold voltage of a cell based on Sb 7 Te 3 /ZnSb are 6.9 μA and 1.9 V, respectively. The lower RESET power is presented in the PCM cells of Sb 7 Te 3 /ZnSb films, benefiting from its high resistivity. [ABSTRACT FROM AUTHOR]

Superlattice-like film (SLF) was formed alternately by Ti 0.43 Sb 2 Te 3 (TST) and TiN, and TST is employed as phase change layers and TiN is employed as isolation layers of TST film. Comparing with single TST film with the same thickness, SLF owns higher data retention, higher phase change speed (5 ns) and endurance up to 1 × 10 5 cycles, and its power consumption of reset operation is significantly decreased by 65.2%. Two-dimensional thermal transient simulation of reset operation indicates that SLF-based device owns higher heating efficiency than 30-nm-thick TST-based device. [ABSTRACT FROM AUTHOR]

The contradictory between thermal stability and operation speed has traditionally been the restriction to apply phase change memory (PCM) in the harsh condition. For providing a feasible solution, in this paper, Ru-modification is introduced to boost the data retention of Sb 2 Te 3 without sacrificing the operation speed over the conventional Ge 2 Sb 2 Te 5 compound. The both experimental and simulation results indicate that Ru locates at the grain boundary to inhibit the formation of large grains. Several performance of the device was enhanced, including: ultra-high 10-year data retention above 200 °C, lower Reset voltage about 1.9 V at 100 ns pulse width and a fast operation speed of 6 ns. Refined grains and smaller density change contributed to the reduced voltage and increased endurance. These findings demonstrated that PCM based Ru doped Sb 2 Te 3 will be a potential application in high performance memories. [Display omitted] • Ru-modification is introduced to boost data retention of Sb 2 Te 3 without sacrificing operation speed. • Ru locates at the grain boundary proved through the both experimental and simulation. • The temperature for 10-year data retention of Ru 0.08 (Sb 2 Te 3) 0.92 is up to 200 °C. • Ru 0.08 (Sb 2 Te 3) 0.92 possesses Reset voltage of 1.9 V at 100 ns pulse width and operation speed of 10 ns. [ABSTRACT FROM AUTHOR]

Transition metal doping is an effective strategy to improve the properties of phase-change random access memory (PCRAM), while the underlying mechanism remains to be sufficiently investigated. Herein, a Cr-doped Sb 2 Te film is fabricated by co-sputtering and the enhancement mechanism of Cr-doping is deeply investigated by experiments and first-principles calculations. The Cr x Sb 2 Te film exhibits excellent performances involving high crystallization temperature (238.9 °C) and good data retention (10 years @161.7 °C) for Cr 0.56 Sb 2 Te, low density change rate (3.8%) and high reversible switching speed (5 ns) for Cr 0.29 Sb 2 Te, providing a variety of options for different applications. The calculated results show that Cr atoms preferentially substitute the Sb1 site and the Cr Te bonds display a stronger ionic bond character in contrast to the covalent bonded Sb Te, thus improving the crystalline phase stability and crystallization temperature. Moreover, ab initio molecular dynamics simulations demonstrate that in the amorphous phase Cr atoms locate in defective octahedral coordination. Meanwhile, the homopolar Sb Sb wrong bond increased with Cr doping and the Cr atoms tend to form tight cluster in the amorphous phase which could benefit for the fast phase-change speed. Our present findings of Cr 0.29 Sb 2 Te PCRAM device clearly reveal the enhancement mechanism by Cr doping which provides guidance for developing high-performance PCRAM devices. [Display omitted] • High crystallization temperature and good data retention of Cr 0.56 Sb 2 Te presented. • Reversible switching of the Cr 0.29 Sb 2 Te-device is 5 ns with cycling of 105 times. • Low density change rate (3.8%) of the Cr 0.29 Sb 2 Te is presented. • Experiments and theoretical calculations revealed the enhancement mechanism. [ABSTRACT FROM AUTHOR]

• The Ga-doped GaGST material has a great improvement in thermal stability, which has a significant promotion effect on the enhancement of the data retention ability of the phase change memory. • The density change of GaGST material before and after crystallization is smaller than that of GST material, which is beneficial to the improvement of the stability of the phase change material after multiple phase changes. • Phase change memory devices based on GaGST materials have extremely low power consumption. • Compared with GST materials, GaGST has a faster crystallization speed (6 ns). In this paper, GaGST films with different Ga contents were prepared by co-sputtering of Ge 3.4 Sb 2.3 Te 5 target and Ga 2 Ge 3.8 Sb 2.3 Te 5 target to obtain a high-speed and low-power phase change material. The present data emphasize that compared with Ge 2 Sb 2 Te 5 , Ga 0.4 Ge 3.5 Sb 2.3 Te 5 exhibits a higher crystallization temperature(193 °C) and better data retention ability (108 °C for 10 years). XPS results show that Ga and Sb combine to form GaSb, and it reduces the density change after crystallization of GaGST material to 2.7%. At the same time, it has a smaller grain size(∼5–10 nm) and a lower drift(<0.059). Furthermore, the behavior of reversible phase change can be realized by a 6 ns width electric pulse, and the power consumption under the action of this pulse only needs an ultra-low power consumption of 0.16pJ. The results of materials and devices show that Ga 0.4 Ge 3.5 Sb 2.3 Te 5 is a very suitable material for phase-change memory(PCM). [Display omitted] [ABSTRACT FROM AUTHOR]

• Based on the alloy strategy, Er 0.17 Sb 2 Te compound is screened out. • Er 0.17 Sb 2 Te shows high comprehensive performance in phase-change memory. • Origin of high thermal stability proposed to the Er 0.17 Sb 2 Te compound has been discussed. • Effect of replacing Sb by Er on physical properties of Er 0.17 Sb 2 Te compound is analyzed. To date, operation speed and data retention are still bottlenecks for phase-change memory. Doping impurity is a practical strategy to improve these performances of phase-change memory. Here, to avoid the precipitation of impurity, we choose erbium (Er) dopant due to the most matched structure with parental Sb 2 Te (EST), which is manifested by both experimental and simulation results that Er locates at lattice position. The device tests show the excellent comprehensive performances: operation speed as fast as 6 ns and 10-year data retention as high as 121 °C. This excellent amorphous thermal stability stems from the strong Er Te bonds, and these stable local patterns stabilize glassy states and result in high stability. Our study not only demonstrates that the performance of designed EST meets the requirement of phase-change memory, but also provides general doping rules to obtain better comprehensive performance. [ABSTRACT FROM AUTHOR]

• Data retention of Re doped Sb 2 Te (RST) was remarkably increased to 152 °C@10 years. • Density change and power consumption of RST are largely reduced. • Operation speed of RST based device is as fast as 10 ns. Sb 2 Te material is an important base material for phase change memory or optical data storage, but the poor amorphous stability of Sb 2 Te severely limits its application. In this work, we proposed a superhard and infusible Rhenium (Re) doped Sb 2 Te (RST) phase change material to improve the properties of Sb 2 Te. The data retention of RST was remarkably increased to 152 °C@10 years, which is much higher than those of traditional Ge 2 Sb 2 Te 5 (87 °C@10 years) and Sb 2 Te (56 °C@10 years). The operation speed of the RST based device is as fast as 10 ns and the resistance ratio is more than 102 times. The density change of RST (4.2%) is smaller than those of Ge 2 Sb 2 Te 5 (6.5%) and Sb 2 Te (5.7%). Furthermore, the operation voltage and power consumption of RST based device are much lower than those of Ge 2 Sb 2 Te 5 and Sb 2 Te based devices. The results indicate that the RST is a promising material for high performance phase change memory or optical data storage applications. [ABSTRACT FROM AUTHOR]

• Compared with GeSb, the T c increased from 197 °C of GeSb to 233 °C of V 2 O 5 /Ge 8 Sb 92. • The data retention temperature for ten years of V 2 O 5 (4 nm)/Ge 8 Sb 92 (6 nm) is 171.2 °C. • The larger band gap E g makes V 2 O 5 /Ge 8 Sb 92 have higher R a and lower power consumption. • After phase transformation, the volume change of V 2 O 5 /Ge 8 Sb 92 is smaller than GST. In this paper, the superlattice-like V 2 O 5 /Ge 8 Sb 92 films are studied. Compared with Ge 8 Sb 92 film, V 2 O 5 /Ge 8 Sb 92 films have a high crystallization temperature (~233 °C), a large amorphous resistance (~3.4 × 107 Ω) and good data retention temperature (~171.2 °C) for ten years. The volume change rate of V 2 O 5 /Ge 8 Sb 92 superlattice-like film is only 1.855% during the crystallization, which can guarantee a better contact with the electrode when it is applied in the phase-change memory. By adding of V 2 O 5 interlayers, the thermal stability and reliability of Ge 8 Sb 92 film have been greatly improved. [ABSTRACT FROM AUTHOR]

Sb-rich CuSbTe material is proposed to meet the requirements of low-power consumption and high-speed of phase change memory application. Sb-rich CuSbTe material is based on Sb-rich SbTe (Sb 3 Te) material which has a fast crystallization speed. The poor amorphous thermal stability of Sb 3 Te material can be solved by the addition of Cu. Cu 0.25 Sb 3 Te-based device is expected to achieve fast access speed (6 ns) and maintain a high data retention (10-year: 85 °C) in comparison with that of Ge 2 Sb 2 Te 5 (10-year: 78 °C). With the doping of Cu, the power consumption and the grain size of Sb 3 Te-based device are greatly reduced. Under the pulse width of 6 ns, the RESET voltage is only 4.1 V. Moreover, the operation cycles is close to 1 × 105, and the resistance ratio is nearly two orders of magnitude. Finally, the XRD, TEM and XRR measurements were carried out to obtain the microscopic analysis for Cu 0.25 Sb 3 Te alloy. [ABSTRACT FROM AUTHOR]