Data Retention Ability Research Articles

Infinite Lattice Learner: an ensemble for incremental learning

The state of the art in supervised learning has developed effective models for learning, generalizing, recognizing faces and images, time series prediction, and more. However, most of these powerful models cannot effectively learn incrementally. Infinite Lattice Learner (ILL) is an ensemble model that extends state-of-the-art machine learning methods into incremental learning models. With ILL, even batch models can learn incrementally with exceptional data retention ability. Instead of continually revisiting past instances to retain learned information, ILL allows existing methods to converge on new information without overriding previous knowledge. With ILL, models can efficiently chase a drifting function without continually revisiting a changing dataset. Models wrapped in ILL can operate in continuous real-time environments where millions of unique samples are seen every day. Big datasets too large to fit in memory, or even a single machine, can be learned in portions. ILL utilizes an infinite Cartesian grid of points with an underlying model tiled upon it. Efficient algorithms for discovering nearby points and lazy evaluation make this seemingly impossible task possible. Extensive empirical evaluation reveals impressive retention ability for all ILL models. ILL similarly proves its generalization ability on a variety of datasets from classification and regression to image recognition.

Characterization of Ge ions implantation in Sb2Te3 thin films for high speed phase change memory application

Ge ion implantation is adopted for doping of Sb2Te3 thin films and modifying the amorphous to crystal transition kinetics. The crystallization temperatures, crystallization activation energies of crystallization, and thermal stability improve with the Ge dose increasing from 5 × 1015 to 3.0 × 1016 Ge-ions/cm2. In the case of 1.0 × 1016 Ge-ions/cm2 dose, GexSb2Te3 phase change material exhibits a higher crystallization temperature (∼180 °C), a larger crystallization activation energy (∼3.7 eV), and a better data retention ability (∼102 °C for 10 years) in comparison with Ge2Sb2Te5. A reversible switching between Set and Reset can be realized by an electric pulse width as short as 10 ns for GexSb2Te3 based phase change memory.

The impact of vacancies on the stability of cubic phases in Sb\u2013Te binary compounds

Data retention ability and number of cycles are key properties of phase change materials in applications. Combining in situ heating transmission electron microscopy with ab initial calculations, we investigated the phase transitions of binary Sb–Te compounds. The calculations indicated that the vacancies in Te sites destroyed the framework of the cubic phase, which agrees well with the absence of cubic phases observed during in situ heating experiments when the Sb concentration exceeded 50%. In contrast, the vacancies in Sb sites stabilized the cubic structure. Further analysis of the charge density maps revealed that the distribution of antibonding electrons may be the origin of the driving force for structural transitions. Furthermore, our results also showed that reducing the vacancies greatly increased the phase transition temperatures of both the amorphous-cubic and cubic-trigonal phases and therefore may improve the data retention ability and cyclability of phase change materials. This result also implies that doping Sb–Te compounds may provide an approach to discover novel phase change materials by reducing the amount of vacancies.

Light assisted multilevel resistive switching memory devices based on all-inorganic perovskite quantum dots

All-inorganic perovskite quantum dots (APQDs) have emerged as excellent materials which have been widely used in numerous micro-nano photoelectric devices. However, resistive random access memory (RRAM) devices based on APQDs are relatively scarce. In this work, RRAM based on CsPbBr3 APQDs prepared by the solution processed method was fabricated at room temperature. The sandwich structure memory device shows high reproducibility, good data retention ability, and light assisted multilevel storage capability. The resistance ratio (ON/OFF) of the RRAM device between the high resistance state and the low resistance state reaches almost 107. Additionally, the device exhibits high performances under low power consumption—low reading voltage (−0.3 V) and operation voltage (−2.4 V/1.55 V). It is suggested that the connection and rupture of conducting filaments, which are formed by Br vacancies under an electric field, are responsible for the resistive switching effect. Our work provides an opportunity to develop the next generation high-performance and stable nonvolatile memory devices.

Write once read many times resistance switching memory based on all-inorganic perovskite CsPbBr3 quantum dot

Write Once Read Many (WORM) Memory, as one of the most important nonvolatile memory type, has widespread used in a variety of permanent storage applications in the Big Data age. As an excellent material, CsPbBr3 quantum dots have widely used in a lot of photoelectric devices, but CsPbBr3 quantum dots based memory device remain to be studied. In this work a WORM memory device based on CsPbBr3 quantum dots is demonstrated. The CsPbBr3 QDs based WORM shows great reproducibility, good data retention ability, irreversible electrical transition from the high resistance state (HRS) or OFF state to the low resistance state (LRS) or ON state and the resistance ratio (ON/OFF) can reach almost 104. Additionally, the device exhibits high performances under low power consumption — low reading voltage (−0.5 V) and writing voltage (−1.1V). To study the CsPbBr3 QDs based WORM provides an opportunity to develop the next generation high-performance and stable WORM devices.

A Photostimulated BaSi2O5:Eu2+,Nd3+ Phosphor‐in‐Glass for Erasable‐Rewritable Optical Storage Medium

AbstractUp‐to‐date optical storage technology calls for large memory capacity, expanded storage dimension, rewritable capability, low cost, and high energy efficiency, which poses stringent requirements on the storage medium. In this study, a novel BaSi2O5:Eu2+,Nd3+ photostimulated luminescence (PSL) phosphor is developed and then made into phosphor‐in‐glass (PiG) storage medium. Upon ultraviolet light irradiation (write‐in), the generated electrons are captured by the traps, which can be further released by thermal or near‐infrared laser stimulation (read‐out). An insightful investigation is carried out to establish the relationship between trap properties and PSL performance. Demonstration application confirmed the intensity‐multiplexing optical information (including the designed bar code, quick response (QR) code, graphic patterns, and binary data) encoding/decoding. Remarkably, BaSi2O5:Eu2+,Nd3+ PSL PiG show excellent erasable‐rewritable capability thanking to the admirable anti‐ultraviolet property in glass host, as well as good optical data retention ability owing to the spatially isolated deep traps. Hopefully, the present work can push forward the research progress of PSL material and its practical application in optical storage.

Al-Sb-Ge phase change material: A candidate for multilevel data storage with high-data retention and fast speed

The phase change memory with Al-Sb-Ge alloy is investigated for the feasibility of embedded system and the potential possibility of multilevel data storage. The Al15Sb53Ge32 compound has a high crystallization temperature (333 °C) and outstanding data retention ability (260 °C). Ge atoms inhibit crystal growth to enhance thermal stability and Al15Sb53Ge32 contains sequential crystallization of Sb-rich and Ge regions in two-step crystallization process. Remarkably, the device presents a fast speed of 50 ns and endurance up to 2.3 × 104 cycles. At the same time, a reliable tripe-level resistance state of the phase change memory cell is observed.

Crystallization Process of Superlattice-Like Sb/SiO2 Thin Films for Phase Change Memory Application**Supported by the National Natural Science Foundation of China under Grant No 11774438, the Natural Science Foundation of Jiangsu Province under Grant No BK20151172, the Changzhou Science and Technology Bureau under Grant No CJ20160028, the Qing Lan Project, the Opening Project of State Key Laboratory of Silicon Materials under

After compositing with SiO2 layers, it is shown that superlattice-like Sb/SiO2 thin films have higher crystallization temperature (∼240°C), larger crystallization activation energy (6.22 eV), and better data retention ability (189°C for 10 y). The crystallization of Sb in superlattice-like Sb/SiO2thin films is restrained by the multilayer interfaces. The reversible resistance transition can be achieved by an electric pulse as short as 8 ns for the Sb(3 nm)/SiO2(7 nm)-based phase change memory cell. A lower operation power consumption of 0.09 mW and a good endurance of 3.0 × 106 cycles are achieved. In addition, the superlattice-like Sb(3 nm)/SiO2(7 nm) thin film shows a low thermal conductivity of 0.13 W/(m·K).

High performance Al3Sc alloy doped Al3Sc–Sb2Te chalcogenides for phase change memory application

An Al3Sc alloy doped Al3Sc–Sb2Te chalcogenide was put forward to avoid oxidation of pure Sc and enhance data retention ability.

One-step phase transition and thermal stability improvement of Ge2Sb2Te5 films by erbium-doping

The crystallization behavior of Er-doped Ge2Sb2Te5 phase-change materials is investigated systemically for phase change memory application. It is observed that Er dopants can serve as a center for suppression of face-centered-cubic to hexagonal phase transition of Ge2Sb2Te5 films, leading to a one-step crystallization process. The crystallization temperature, 10-year data retention ability and crystalline resistance of Ge2Sb2Te5 films can be significantly increased. Raman spectra suggest that GeTe component is mainly responsible for the phase transition in Er-doped Ge2Sb2Te5 films.

Improved thermal stability of Sb materials by SiO2 doping for ultra-fast phase change memory application

SiO2-doped Sb material is proved to be a promising candidate for phase change memory (PCM) use because of its high crystallization temperature (∼239 °C), large crystallization activation energy (4.05 eV), and good data retention ability (162 °C for 10 years). The band gap is broadened and the grain size is refined by SiO2 doping. The reversible resistance transition can be achieved by an electric pulse as short as 5 ns for the PCM cell based on SiO2-doped Sb material. A lower operation power consumption (the energy for RESET operation 1.1 × 10−11 J) is obtained. In addition, SiO2-doped Sb material shows a good endurance of 2.5 × 105 cycles.

A novel single-ended 9T FinFET sub-threshold SRAM cell with high operating margins and low write power for low voltage operations

Recently, SRAM for sub-threshold operation is in developing stage for ultra-low power applications and portable devices. It aims to support high operating margins and high performance with low power applications under process and temperature variations. In this paper, a novel FinFET based 9T SRAM cell is proposed, which employs single ended bit-line scheme to perform read and write operations in the near-threshold region, without any boosted power supply and write assist circuitry. The write-ability, write power and write time have been improved by breaking down the feedback of two cross- coupled inverter pairs using both transistors (M4 and M5) to cut off at write mode, thereby obviating write as well as read constraints on semiconductor device dimensions. Apart from this, write-ability and write time improved substantially by using low threshold voltage (Vt) transmission gate as an access transistor. The read time and read margin have also improved by separate low Vt decouple read transistor (M9). The different characteristics are compared at 7nm, 10nm, 14nm, 16nm, and 20nm in HSPICE at 0.5 Vdd. Furthermore, the various cell parameters are investigated at voltages from 0.3 to 0.9V and at a temperature range of −35 to 100°C. The experimental results show that proposed 9T cell achieves 1.86 × and 1.06 × better write-ability as compared to 7T cell and 8T cell respectively. The read stability is 2.56 × of 7T and 1.05 × of 8T. The data retention ability is 1.57× of 7T and 1.05× of 8T. The write power is 30.49% of 8T and 5.01% of a 7T. In addition, it takes 3.57× and 1.77× less write time when compared to 8T cell and 7T cell respectively at 0.5V using 20nm process technology.

O-doped Sb materials for improved thermal stability and high-speed phase change memory application

The O-doped Sb materials were proved to have higher crystallization temperature (∼205 °C), larger crystallization activation energy (3.95 eV) and better data retention ability (143 °C for 10 years). The band gap was broadened by O-doping and the grain size was refined. The formation of Sb oxide increased the binding energy. The fast phase change speed was obtained for O-doped Sb materials by picosecond laser technology. After O-doping, the phase change film had a smaller surface roughness (1.05 nm).

Enhanced Crystallization Behaviors of Silicon-Doped Sb2Te Films: Optical Evidences.

The optical properties and structural variations of silicon (Si) doped Sb2Te (SST) films as functions of temperature (210–620 K) and Si concentration (0–33%) have been investigated by the means of temperature dependent Raman scattering and spectroscopic ellipsometry experiments. Based upon the changes in Raman phonon modes and dielectric functions, it can be concluded that the temperature ranges for intermediates and transition states are estimated to 150, 120, 90, and 0 K, corresponding to ST, SST25%, SST28%, and SST33% films, respectively. The phenomenon also can be summarized by the thermal evolutions of interband electronic transition energies (En) and partial spectral weight integral (I). The disappearance of intermediate (INT) state for SST33% film between amorphous (AM) and hexagonal (HEX) phases can be attributed to the acceleratory crystallization of HEX phase by Si introduction. It illustrates that the risk of phase separation (Sb and Te) during the cyclic phase-change processes decreases with the increasing Si concentration. The enhanced crystallization behaviors can optimize the data retention ability and the long term stability of ST by Si doping, which are important indicators for phase change materials. The performance improvement has been analyzed qualitatively from the optical perspective.

Improved thermal stability of N-doped Sb materials for high-speed phase change memory application

Compared with pure Sb, N-doped Sb material was proved to be a promising candidate for the phase change memory (PCM) use because of its higher crystallization temperature (∼250 °C), larger crystallization activation energy (3.53 eV), and better data retention ability (166 °C for 10 years). N-doping also broadened the band gap and refined grain size. The reversible resistance transition could be achieved by an electric pulse as short as 8 ns for the PCM cell based on N-doped Sb material. A lower operation power consumption (the energy for RESET operation 2.2 × 10−12 J) was obtained. In addition, N-doped Sb material showed a good endurance of 1.8 × 105 cycles.

Si/Sb superlattice-like thin films for ultrafast and low power phase change memory application

After compositing with Si, the superlattice-like (SLL) Si/Sb thin film had higher crystallization temperature (~231°C), larger crystallization activation energy (2.95eV), and better data retention ability (126°C for 10years). The crystallization of Sb in SLL Si/Sb thin films was restrained by the multilayer interfaces. The reversible resistance transition could be achieved by an electric pulse as short as 10ns for [Si(22nm)/Sb(2nm)]2-based PCM cell. A lower operation power consumption of 0.02mW and a good endurance of 1.0×105cycles were achieved. In addition, SLL [Si(22nm)/Sb(2nm)]2 thin film showed a low thermal conductivity of 0.11W/(m·K).

Investigation of Ni Doped Ge-Te Materials for High Temperature Phase Change Memory Applications

Ni-doped Ge-Te (Ni-GT) material was proposed and investigated for phase change random access memory (PCRAM) applications. With Ni addition, the crystallization temperature, data retention ability and crystallization speed were obviously improved. The surface roughness of crystalline Ni-GT films was decreased by Ni incorporation. Moreover, temperature dependent transmission electron microscopy (TEM) was applied to investigate the phase change behavior of Ni-GT films. All the experimental results demonstrated that Ni-GT material has potential for high-speed PCRAM applications in high temperature environment.

Investigation of SiC doped Sb3Te alloy for high-speed and high-thermal stability phase change random access memory applications

Silicon carbide (SiC) doped Sb3Te materials have been investigated for realizing high speed blending with admirable endurance and excellent stability in phase-change applications. (SiC)0.85-Sb3Te alloy is considered to be a potential candidate in view of its high crystallization temperature (199.6°C) and a good data retention ability (118.5°C for 10 years). The prominent advantages can be seen in comparison with those of pure Sb3Te and Ge2Sb2Te5. Moreover, phase change memory cell based on (SiC)0.85-Sb3Te achieves ultrafast reversible operation (5ns) and good endurance (3.9×104 cycles) easily due to dopants' uniform distribution and a key role in grain refinement.

Improved phase change behavior of Sb2Se material by Si addition for phase change memory

Compared with Sb2Se, Si–Sb–Se material is proved to be a promising candidate for phase change memory (PCM) use because of its higher crystallization temperature (~230°C), larger crystallization activation energy (3.25eV), and better data retention ability (168°C for 10years). Furthermore, the fast crystallization time 3.30ns is obtained for Si0.20(Sb2Se)0.80 material by the picosecond laser technique. The set switching is realized with low threshold current 6.9μA and voltage 1.80V, respectively. The reverse resistance transition can be achieved by an electric pulse as short as 8ns for Si0.20(Sb2Se)0.80-based PCM cell.

High thermal stable and fast switching Ni-Ge-Te alloy for phase change memory applications

Ni-Ge-Te phase change material is proposed and investigated for phase change memory (PCM) applications. With Ni addition, the crystallization temperature, the data retention ability, and the crystallization speed are remarkably improved. The Ni-Ge-Te material has a high crystallization temperature (250 °C) and good data retention ability (149 °C). A reversible switching between SET and RESET state can be achieved by an electrical pulse as short as 6 ns. Up to ∼3 × 104 SET/RESET cycles are obtained with a resistance ratio of about two orders of magnitude. All of these demonstrate that Ni-Ge-Te alloy is a promising material for high speed and high temperature PCM applications.