Universal memory based on phase-change materials: From phase-change random access memory to optoelectronic hybrid storage*

Abstract

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.

Toward Memristive Phase‐Change Neural Network with High‐Quality Ultra‐Effective Highly‐Self‐Adjustable Online Learning

“…[40][41][42][43][44][45] The PCM operations, based on the reversible switching between the crystallized state and the disordered amorphous state of a chalcogenide alloy (typically a telluride), exhibit a marked contrast in the electrical conductivity and optical reflectivity, and are ultra-rapid, on the several ten-nanosecond timescales. [46][47][48][49][50][51] Moreover, experiments have revealed that the "priming" of crystalline nuclei in the amorphous state, which is denoted as the primed state, can lead to ultra-rapid set (crystallization) operations. [52][53][54] The primed state can be distinguished from the amorphous state with regard to their altered responses to thermal or electric stimuli, although a negligible variation occurs in the electrical conductance.…”

Bio‐Inspired 3D Artificial Neuromorphic Circuits

“…[194,210,211] Apart from the abovementioned resistive memristors based on ionic conductors and metal oxides, memristors composed of phase change materials (PCM) have also become the topic of intense investigations in recent years. [212][213][214][215] Analogous to the resistance variation controlled by the filament path in resistive memristors, the tuned amorphous and crystalline states can enable large resistance contrast in PCM memristors. [216,217] The nonvolatile memory based on PCM is particularly suitable for mapping analog synaptic weights due to the continuously variable conductance of the PCM.…”

Investigation of Different Oxygen Partial Pressures on MgGa2O4-Resistive Random-Access Memory

“…While nonvolatile flash memories encounter charge storage problems originating from their fundamental scaling limits, which hinder their implementation on further size miniaturization . To overcome the bottleneck, enormous emerging nonvolatile memories, such as phase change random access memory, magnetoresistive RAM, and resistive RAM (RRAM) are viewed as the next promising candidates or alternatives by their excellent memory performance and requirements. Among them, RRAMs exhibit lots of benefits, including low fabrication cost, a simple metal–insulator–metal (MIM) structure, complementary metal–oxide–semiconductor compatibility, small effective cell size of 4 F 2 , fast switching speed, high cycling endurance, and favorable retention time. − Transition metal oxide RRAMs such as HfO 2 , , TiO 2 , , NiO, , and ZnO , have been extensively studied and researched.…”