Biodegradable albumen dielectrics for high-mobility MoS2 phototransistors.

This work demonstrates the fabrication and characterization of single-layer MoS2 field-effect transistors using biodegradable albumen (chicken eggwhite) as gate dielectric. By introducing albumen as an insulator for MoS2 transistors high carrier mobilities (up to ~90 cm2 V-1 s-1) are observed, which is remarkably superior to that obtained with commonly used SiO2 dielectric which we attribute to ionic gating due to the formation of an electric double layer in the albumen MoS2 interface. In addition, the investigated devices are characterized upon illumination, observing responsivities of 4.5 AW-1 (operated in photogating regime) and rise times as low as 52 ms (operated in photoconductivity regime). The presented study reveals the combination of albumen with van der Waals materials for prospective biodegradable and biocompatible optoelectronic device applications. Furthermore, the demonstrated universal fabrication process can be easily adopted to fabricate albumen-based devices with any other van der Waals material.

Combining Freestanding Ferroelectric Perovskite Oxides with Two-Dimensional Semiconductors for High Performance Transistors.

We demonstrate the fabrication of field-effect transistors based on single-layer MoS2 and a thin layer of BaTiO3 (BTO) dielectric, isolated from its parent epitaxial template substrate. Thin BTO provides an ultrahigh-κ gate dielectric effectively screening Coulomb scattering centers. These devices show mobilities substantially larger than those obtained with standard SiO2 dielectrics and comparable with values obtained with hexagonal boron nitride, a dielectric employed for fabrication of high-performance two-dimensional (2D) based devices. Moreover, the ferroelectric character of BTO induces a robust hysteresis of the current vs gate voltage characteristics, attributed to its polarization switching. This hysteresis is strongly suppressed when the device is warmed up above the tetragonal-to-cubic transition temperature of BTO that leads to a ferroelectric-to-paraelectric transition. This hysteretic behavior is attractive for applications in memory storage devices. Our results open the door to the integration of a large family of complex oxides exhibiting strongly correlated physics in 2D-based devices.