Ambipolar Resistive Switching in an Ultrathin Surface-Supported Metal–Organic Framework Vertical Heterojunction

Abstract

Memristors (MRs) are considered promising devices with the enormous potential to replace complementary metal-oxide-semiconductor (CMOS) technology, which approaches the scale limit. Efforts to fabricate MRs-based hybrid materials may result in suitable operating parameters coupled to high mechanical flexibility and low cost. Metal–organic frameworks (MOFs) arise as a favorable candidate to cover such demands. The step-by-step growth of MOFs structures on functionalized surfaces, called surface-supported metal–organic frameworks (SURMOFs), opens the possibility for designing new applications in strategic fields such as electronics, optoelectronics, and energy harvesting. However, considering the MRs architecture, the typical high porosity of these hybrid materials may lead to short-circuited devices easily. In this sense, here, it is reported for the first time the integration of SURMOF films in rolled-up scalable-functional devices. A freestanding metallic nanomembrane provides a robust and self-adjusted top mechanical contact on the SURMOF layer. The electrical characterization reveals an ambipolar resistive switching mediated by the humidity level with low-power consumption. The electronic properties are investigated with density functional theory (DFT) calculations. Furthermore, the device concept is versatile, compatible with the current parallelism demands of integration, and transcends the challenge in contacting SURMOF films for scalable-functional devices.

Room‐Temperature Negative Differential Resistance in Surface‐Supported Metal‐Organic Framework Vertical Heterojunctions

“…In Figure 1e, an LSCM image of the active device area (dotted region from Figure 1c) is presented in detail. The top contact realized by the microtube results in different geometric and effective device contacting areas ( A GEO and A EFF ) of about 8 µm 2 and 10 3 nm 2 , [ 6 ] respectively. These values are expected considering the soft and self‐adjusted nature of the rolled‐up nanomembrane and the involved interfaces’ topography.…”

“…[ 1,2 ] The grazing incidence X‐ray diffraction (GIXRD) pattern shown in Figure 1f and Figure S4 (Supporting Information) reveals the presence of crystalline HKUST‐1 thin films. [ 1,2,6 ] Well‐orientated HKUST‐1 films have been reported on COOH‐terminated organic surfaces. [ 42,43 ] However, the two preferential orientations seen in Figure 1f and Figure S4 (Supporting Information) are consequences of the short‐chain length from the SAM layer (6‐mercaptohexanoic acid) and the low SURMOF thickness.…”

“…SURMOFs have good mechanical flexibility, [ 3 ] high versatility, and are well suited for integration into devices and systems in various application fields. [ 4,5 ] In particular, these structures opened new perspectives for the realization of novel electronic devices, e.g., as resistive switchers, [ 6–9 ] field‐effect transistors, [ 10 ] and optoelectronics. [ 11–14 ] Despite these interesting advances, the full potential of this class of hybrid materials has not yet been fully explored, e.g., quantum electronic tunneling phenomena, which may lead to negative differential resistance (NDR), have not been reported for SURMOF‐based devices.…”

“…[ 4,5 ] Furthermore, the electrical properties of these crystalline and porous thin films can be further modified by loading guest molecules and ions inside the pores. [ 6,11,39,40 ]…”

“…[ 2 ] The electronic structure of HKUST‐1 SURMOF is susceptible to the presence of water, causing the appearance of additional states in the bandgap region. [ 6 ] Thus, by adequately tailoring external conditioning parameters, the band‐structure of HKUST‐1 SURMOFs can be designed to explore unprecedented quantum electronic tunneling phenomena.…”