Silicon-Controlled Rectifier Embedded Diode for 7 nm FinFET Process Electrostatic Discharge Protection.

A new silicon-controlled rectifier embedded diode (SCR-D) for 7 nm bulk FinFET process electrostatic discharge (ESD) protection applications is proposed. The transmission line pulse (TLP) results show that the proposed device has a low turn-on voltage of 1.77 V. Compared with conventional SCR and diode string, the proposed SCR-D has an additional conduction path constituting by two additional inherent diodes, which results in a 1.8-to-2.2-times current surge capability as compared with the simple diode string and conventional SCR with the same size. The results show that the proposed device meets the 7 nm FinFET process ESD design window and has already been applied in actual circuits.

Dielectric breakdown of 2D muscovite mica.

Localized electrical breakdown (BD) measurements are performed on 2D muscovite mica flakes of ~ 2 to 15 nm thickness using Conduction Atomic Force Microscopy (CAFM). To obtain robust BD data by CAFM, the probed locations are spaced sufficiently far apart (> 1 µm) to avoid mutual interference and the maximum current is set to a low value (< 1 nA) to ensure severe damage does not occur to the sample. The analyses reveals that 2D muscovite mica has high electrical breakdown strength (12 MV/cm or more) and low leakage current, comparable to 2D hexagonal boron nitride (h-BN) of similar thickness. However, a significant difference compared to h-BN is the very low current necessary to avoid catastrophic damage during the BD event, even for very thin (2-3 nm) flakes. Further, for mica the BD transient always appear to be very abrupt, and no progressive BD process was definitively observed. These marked differences between mica and h-BN are attributed to the poor thermal conductivity of mica.

Using post-breakdown conduction study in a MIS structure to better understand the resistive switching mechanism in an MIM stack.

We apply our understanding of the physics of failure in the post-breakdown regime of high-κ dielectric-based conventional logic transistors having a metal-insulator-semiconductor (MIS) structure to interpret the mechanism of resistive switching in resistive random-access memory (RRAM) technology metal-insulator-metal (MIM) stacks. Oxygen vacancies, gate metal migration and metal filament formation in the gate dielectric which constitute the chemistry of breakdown in the post-breakdown stage of logic gate stacks are attributed to be the mechanisms responsible for the SET process in RRAM technology. In this paper, we draw an analogy between the breakdown study in logic devices and filamentation physics in resistive non-volatile memory.

Standards for the Characterization of Endurance in Resistive Switching Devices.

Resistive switching (RS) devices are emerging electronic components that could have applications in multiple types of integrated circuits, including electronic memories, true random number generators, radiofrequency switches, neuromorphic vision sensors, and artificial neural networks. The main factor hindering the massive employment of RS devices in commercial circuits is related to variability and reliability issues, which are usually evaluated through switching endurance tests. However, we note that most studies that claimed high endurances >106 cycles were based on resistance versus cycle plots that contain very few data points (in many cases even <20), and which are collected in only one device. We recommend not to use such a characterization method because it is highly inaccurate and unreliable (i.e., it cannot reliably demonstrate that the device effectively switches in every cycle and it ignores cycle-to-cycle and device-to-device variability). This has created a blurry vision of the real performance of RS devices and in many cases has exaggerated their potential. This article proposes and describes a method for the correct characterization of switching endurance in RS devices; this method aims to construct endurance plots showing one data point per cycle and resistive state and combine data from multiple devices. Adopting this recommended method should result in more reliable literature in the field of RS technologies, which should accelerate their integration in commercial products.

Localized Probing of Dielectric Breakdown in Multilayer Hexagonal Boron Nitride.

Hexagonal boron nitride (h-BN) has emerged as a promising 2D/layered dielectric owing to its successful integration with graphene and other 2D materials, although a coherent picture of the overall dielectric breakdown mechanism in h-BN is yet to emerge. Here, we have carried out a systematic study using conduction atomic force microscopy to provide insights into the process of defect generation and dielectric degradation in the progressive breakdown (PBD) and hard breakdown (HBD) stages in 2-5 nm thick chemical vapor deposition (CVD)-grown multilayer h-BN films. The PBD and HBD regimes show different behaviors. Under electrical stress in the PBD stage, defects are generated progressively in the h-BN, leading to a gradual reduction of the effective barrier resistance and continuous soft breakdowns (SBDs) of the dielectric material. Random telegraph noise nano-spectroscopy shows that low frequency noise becomes dominant after an SBD event due to the creation of additional defects around the percolation path. We also observe a wide variation in the current-voltage (I-V) breakdown plots in the PBD stage, giving rise to non-Weibull statistical distribution of the breakdown voltage. We attribute this observation to the significant thickness inhomogeneity in the CVD films. At HBD, h-BN materials are always physically removed from the film, leading to the formation of pits at the breakdown location. Interestingly, pit formation is also occasionally observed in the PBD stage under very low current compliances, suggesting that breakdown may proceed by a mixture of defect generation and material removal in h-BN CVD films.

Carbon nanotube membranes with ultrahigh specific adsorption capacity for water desalination and purification.

Development of technologies for water desalination and purification is critical to meet the global challenges of insufficient water supply and inadequate sanitation, especially for point-of-use applications. Conventional desalination methods are energy and operationally intensive, whereas adsorption-based techniques are simple and easy to use for point-of-use water purification, yet their capacity to remove salts is limited. Here we report that plasma-modified ultralong carbon nanotubes exhibit ultrahigh specific adsorption capacity for salt (exceeding 400% by weight) that is two orders of magnitude higher than that found in the current state-of-the-art activated carbon-based water treatment systems. We exploit this adsorption capacity in ultralong carbon nanotube-based membranes that can remove salt, as well as organic and metal contaminants. These ultralong carbon nanotube-based membranes may lead to next-generation rechargeable, point-of-use potable water purification appliances with superior desalination, disinfection and filtration properties.