Asymmetric Dressing of WSe₂ with (Macro)molecular Switches: Fabrication of Quaternary-Responsive Transistors

Abstract

The forthcoming saturation of Moore's law has led to a strong demand for integrating analog functionalities within semiconductor-based devices. As a step towards this goal, we fabricate quaternary-responsive WSe 2 -based field-effect transistors (FETs) whose output current can be remotely and reversibly controlled by light, heat and electric field. A photochromic silaneterminated spiropyran (SP) is chemisorbed on SiO 2 forming a self-assembled monolayer (SAM) that can switch from the SP to the merocyanine (MC) form in response to UV illumination and switch back by either heat or visible illumination. Such SAM is incorporated at the dielectric-semiconductor interface in WSe 2 -based FETs. Upon UV irradiation, a drastic decrease in the output current of 82% is observed and ascribed to the zwitterionic MC isomer acting as charge scattering site. To impart an additional functionality, the WSe 2 top surface is coated with a ferroelectric co-polymer layer based on poly(vinylidene fluoride-cotrifluoroethylene) (P(VDF-TrFE)). Due to its switchable inherent electrical polarization, it can promote either the accumulation or depletion of charge carriers in the WSe 2 channel, thereby 2 inducing a current modulation with 99% efficiency. Thanks to the efficient tuning sparked by the two components and their synergistic effects, the device polarity could be modulated from n-type to p-type. Such a control over the carrier concentration and device polarity is key to develop 2D advanced electronics. Moreover, the integration strategy of multiple stimuliresponsive elements into a single FET allows to greatly enrich its functionality, thereby promoting the development for More-than-Moore technology.

Vertical organic transistors with short channels for multifunctional optoelectronic devices

“…(iii) As of the increasing demand of smart health monitoring, multi-functional sensing devices responding to not only to physical inputs (light, heat and pressure) but also to chemical inputs (ions and gases) require the incorporation of stimuli-responsive molecules in low-power consumption devices. 93…”

Molecular Approach to Engineer Two-Dimensional Devices for CMOS and beyond-CMOS Applications

“…In a recent study, the asymmetric dressing of top and bottom WSe 2 surfaces with ferroelectric P(VDF-TrFE) layer and light-responsive spiropyran molecules enabled the quaternary-stimuli-responsive FETs, which can respond to heat, light, and electric field. 472 The light stimuli can modulate the current of WSe 2 channel by 82% and the electric stimuli can induce the current change by 99%. The carriers in semiconducting WSe 2 layer can be switched from ntype to p-type by synergistically controlling the light and electric stimuli.…”

“…The use of a polymeric ferroelectric gate was later reported for semiconducting 2DMs including MoS 2 , − MoSe 2 , MoTe 2 , − In 2 Se 3 , black phosphorus, and WSe 2 . − For instance, in 2012, Im et al fabricated a MoS 2 FET with 200 nm-thick P­(VDF-TrFE) polymer top-gate . The monolayer MoS 2 device showed good retention properties in both static and dynamic switching, maintaining a high current ratio of ∼5 × 10 3 between HRS and LRS.…”

“…[470][471][472] . For instance, in 2012, Im et al fabricated a MoS2 FET with 200-nm-thick P(VDF-TrFE) polymer topgate.…”

Spiropyran-incorporated honeycomb porous films with reversible multistimuli-responsive properties

“…Inspired by several living creatures that are able to sense and react to environmental stimuli, for example, chameleons and neon tetra fish, stimuli-responsive materials in which selected structures or properties are switched on and off in response to one or more external stimuli such as light, temperature, electric and magnetic field, pH, solvent, ions and moisture have attracted lots of consideration from a broad range of fields from actuators, optical memories, sensors, bioimaging, anticounterfeiting, displays to data storage. [1][2][3][4][5] Incorporating stimuli-responsive compounds into the system is one of the effective ways to endow materials with switchable characteristics. [6][7][8] Accordingly, various types of stimulusresponsive molecules including azobenzene, phenoxyquinone, bisthienylethene and spiropyran (SP) derivatives have been explored so far.…”