Experimental Observation and Mitigation of Dielectric Screening in Hexagonal Boron Nitride Based Resistive Switching Devices

Abstract

Moisture and water penetration is one of the main phenomena altering the electrical characteristics and performance of resistive switching (RS) devices based on metal/insulator/metal nanojunctions. However, the effect of these phenomena in RS devices made of two dimensional (2D) materials has never been studied. In this paper it is shown that 2D materials based RS devices exposed to high relative humidity environments develop dielectric screening effects. The devices measured right after fabrication show a yield of 95% and bipolar RS characteristics, while after exposure to humid environments for two months the yield decreases to 65%. More than 30% of the devices show much lower currents than the fresh counterparts, and at high voltages they exhibit clear dielectric screening effects. This behavior is even more accentuated in RS devices that require the transfer of the 2D material, and we observe that a baking step at 120°C for 5 min can mitigate this effect.

Stability and Repeatability of a Karst-like Hierarchical Porous Silicon Oxide-Based Memristor

“…The phenomenon of the current degradation may be caused by the self-limited effect. During the continuously positive and negative voltage sweeps, self-limited effect results in the excessive accumulation of lithium ions in KLHP silicon oxide, which accelerates the degradation rate and creates a situation useful for cycling endurance. , The lower electric field is not enough to dislodge the lithium ions embedded in the KLHP, but a larger electric field may damage the device during the consecutive voltage sweeps.…”

Recommended Methods to Study Resistive Switching Devices

“…Three kinds of MIM test structures are the most common when studying RS: i) common bottom electrode (BE, Figure a), ii) cross‐point (Figure b), and iii) cross‐bar (Figure c). The first one uses a conductive substrate that serves as common BE for all the MIM cells . Then, an insulating film is deposited on its entire surface and finally several top electrodes (TE) with a specific area can be patterned along the surface of the insulator .…”

“…d) Cross‐sectional TEM image of a 28 nm wide MIM structure. a,b) Reproduced with permission . Copyright 2018, Wiley‐VCH.…”

150 nm × 200 nm Cross‐Point Hexagonal Boron Nitride‐Based Memristors

“…For example, graphene has been used as interfacial layer to avoid the interactions between metallic electrodes and the resistive switching (RS) medium (e.g., oxygen vacancies migration from the insulator to electrodes, and metal ion penetration into the insulator) 12. Other 2D materials like graphene oxide (GO),13–17 black phosphorous (BP),18 molybdenum disulfide (MoS 2 ),19,20 and hexagonal boron nitride ( h ‐BN)21 have been used as RS active medium, and the switching mechanisms have been attributed to the migration of intrinsic atomic species in the 2D material (e.g., O in GO, S in MoS 2 , and B in h ‐BN), and in some cases it is combined with the penetration of metal ions 22. Unfortunately, 2D materials based memristors are still not being taken seriously because: i) most of the works just show proof‐of‐concept RS observations (e.g., no variability data is presented), ii) they use device structures that are not competitive from a technological point of view (e.g., the 2D material is obtained by mechanical exfoliation, the size of the electrodes is too large, >0.01 mm 2 , and/or they use planar MIM configurations that consume too much space and lead to high device‐to‐device variability), and iii) the performance of 2D materials based memristors is still behind that of transition metal oxide (TMO)‐based memristors in terms of switching speed, power consumption, endurance, and retention.…”