The recent commercialization of electronic memories based on phase change materials proved the usability of this peculiar family of materials for application purposes. More advanced data storage and ...computing concepts, however, demand a deeper understanding especially of the electrical properties of the amorphous phase and the switching behaviour. In this work, we investigate the temporal evolution of the current through the amorphous state of the prototypical phase change material, Ge2Sb2Te5, under constant voltage. A custom-made electrical tester allows the measurement of delay times over five orders of magnitude, as well as the transient states of electrical excitation prior to the actual threshold switching. We recognize a continuous current increase over time prior to the actual threshold-switching event to be a good measure for the electrical excitation. A clear correlation between a significant rise in pre-switching-current and the later occurrence of threshold switching can be observed. This way, we found experimental evidence for the existence of an absolute minimum for the threshold voltage (or electric field respectively) holding also for time scales far beyond the measurement range.
Nonvolatile RAM using resistance contrast in phase-change materials or phase-change RAM (PCRAM) is a promising technology for future storage-class memory. However, such a technology can succeed only ...if it can scale smaller in size, given the increasingly tiny memory cells that are projected for future technology nodes (i.e., generations). We first discuss the critical aspects that may affect the scaling of PCRAM, including materials properties, power consumption during programming and read operations, thermal cross-talk between memory cells, and failure mechanisms. We then discuss experiments that directly address the scaling properties of the phase-change materials themselves, including studies of phase transitions in both nanoparticles and ultrathin films as a function of particle size and film thickness. This work in materials directly motivated the successful creation of a series of prototype PCRAM devices, which have been fabricated and tested at phase-change material cross-sections with extremely small dimensions as low as 3 nm × 20 nm. These device measurements provide a clear demonstration of the excellent scaling potential offered by this technology, and they are also consistent with the scaling behavior predicted by extensive device simulations. Finally, we discuss issues of device integration and cell design, manufacturability, and reliability. PUBLICATION ABSTRACT
In this letter, bipolar fast-pulse switching in TiO 2 -based nanocrossbar devices was investigated. A dedicated measurement setup was used to measure the transient currents during 5-ns resistive ...switching. Transient peak currents for the set and reset processes were as high as 200 and 230 μA, respectively. The currents observed during fast-pulse switching are explained and simulated by Joule heating, which is needed for fast oxygen-vacancy movement. The measured transient currents enable a further optimization of resistive switches based on TiO 2 .
In this letter, bipolar fast-pulse switching in Formula Omitted-based nanocrossbar devices was investigated. A dedicated measurement setup was used to measure the transient currents during 5-ns ...resistive switching. Transient peak currents for the set and reset processes were as high as 200 and 230 Formula Omitted, respectively. The currents observed during fast-pulse switching are explained and simulated by Joule heating, which is needed for fast oxygen-vacancy movement. The measured transient currents enable a further optimization of resistive switches based on Formula Omitted.
In this letter, bipolar fast-pulse switching in hbox TiO 2 -based nanocrossbar devices was investigated. A dedicated measurement setup was used to measure the transient currents during 5-ns resistive ...switching. Transient peak currents for the set and reset processes were as high as 200 and 230 mu hbox A , respectively. The currents observed during fast-pulse switching are explained and simulated by Joule heating, which is needed for fast oxygen-vacancy movement. The measured transient currents enable a further optimization of resistive switches based on hbox TiO 2 .
An ultra-thin phase-change bridge (PCB) memory cell, implemented with doped GeSb, is shown with < 100muA RESET current. The device concept provides for simplified scaling to small cross-sectional ...area (60nm 2 ) through ultra-thin (3nm) films; the doped GeSb phase-change material offers the potential for both fast crystallization and good data retention
Switchable metal-insulator-metal (MIM) structures are the key elements for future non-volatile resistive RAM (RRAM) devices. Recently this type of memory device has attracted considerable interest ...due to the prospect of non-volatile data storage combined with low power consumption, excellent scalability and very fast write/read operation. However the physical processes responsible for the fast resistive switching are still under investigation. In this work we will present the replacement of the time consuming quasi-static current driven electroforming process by short voltage pulse induced electroforming. Furthermore resistive switching was measured with voltage pulses down to 5 ns pulse width with an in-situ recording of the current response. The high-frequency measurements provide a deeper insight into the physical background of fast data operation.
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