Conductive Atomic Force Microscope Study of Bipolar and Threshold Resistive Switching in 2D Hexagonal Boron Nitride Films

Abstract

This study investigates the resistive switching characteristics and underlying mechanism in 2D layered hexagonal boron nitride (h-BN) dielectric films using conductive atomic force microscopy. A combination of bipolar and threshold resistive switching is observed consistently on multi-layer h-BN/Cu stacks in the low power regime with current compliance (Icomp) of less than 100 nA. Standard random telegraph noise signatures were observed in the low resistance state (LRS), similar to the trends in oxygen vacancy-based RRAM devices. While h-BN appears to be a good candidate in terms of switching performance and endurance, it performs poorly in terms of retention lifetime due to the self-recovery of LRS state (similar to recovery of soft breakdown in oxide-based dielectrics) that is consistently observed at all locations without requiring any change in the voltage polarity for Icomp ~1–100 nA.

A Review on Dielectric Breakdown in Thin Dielectrics: Silicon Dioxide, High‐k, and Layered Dielectrics

“…As the BD is a stochastic process that always takes place at the weakest location of the area under stress, the currents collected with the probe station should be more representative of the grain boundaries of the polycrystalline CVD‐grown h‐BN sheet, which are known to be defective paths with enhanced conductivity . Interestingly, current fluctuations similar to RTN can be observed at the device level.…”

Functional Non‐Volatile Memory Devices: From Fundamentals to Photo‐Tunable Properties

“…Besides, they demonstrated the underlying memory mechanism which is due to the formation/rupture of CFs consist of Ag − and V s − . Furthermore, besides traditional 2D materials mentioned above, many novel 2D materials and hybrid composites, such as 2D perovskite, WO 3 , and hBN‐MoS 2 nanocomposite, were also investigated to fabricate ReRAM which possess superior performance and diverse resistive switching mechanism …”

“…In 2016, Lee et al fabricated ultrathin flexible resistive switching memory based on 2D h‐BN, where the h‐BN films were grown through chemical vapor deposition (CVD), and the switching mechanism was investigated with CAFM and ex‐situ TEM . As shown in Figure , they compared switching characteristics among three similar device structures with different top electrodes or bottom electrodes to prove the resistive switching effect are governed primarily by ultrathin 2D h‐BN materials, which is also investigated by Ranjan et al with conductive Atomic Force Microscope (CAFM) recently . Furthermore, they figured out the best performance device with structure of Ag/h‐BN/Cu foil/PET which possess high ON/OFF ratio with durable retention, low energy consumption, and good endurance.…”

Boron Vacancies Causing Breakdown in 2D Layered Hexagonal Boron Nitride Dielectrics

“…Hexagonal boron nitride (h-BN) is a promising 2D layered insulator with high thermal, mechanical and chemical stability, matching lattice constant to graphene and a van der Waals structure that allows for easy integration and realization of fully-2D nanodevices. There have been a few recent reports on h-BN from a reliability perspective which have: measured the breakdown (BD) field strength [1]; probed the electrical defects using random telegraph noise techniques [2,3]; provided physical evidence of the sequential removal of layers during BD with a Weibull distribution to represent BD statistics; observed pit formation in multi-layer h-BN after BD [4]; suggested the presence of bimodality in the progressive BD trends due to competition between lateral wear-out and multi-layer BD [5]; examined the resonant electron tunneling and electron percolation through local bandgap states within h-BN [6]; and studied the charge trapping and impact ionization phenomena in h-BN at low and high fields [7]. However, there is a lack of insight into the statistical nature and defect chemistry of BD in h-BN [8], which is the focus of this study.…”