Natural layered phlogopite dielectric for ultrathin two-dimensional optoelectronics

TL;DR

This paper demonstrates that natural phlogopite mica can serve as an effective high-k dielectric for 2D electronics, enabling high-performance transistors and photodetectors with superior characteristics.

Contribution

It introduces naturally occurring phlogopite mica as a robust, earth-abundant high-k dielectric for 2D semiconductors, showing its compatibility and performance benefits.

Findings

Transistors with subthreshold swing down to 100 mV/dec

Phototransistors with responsivity up to 3.3x10^4 AW^-1

High dielectric strength and interface quality comparable to oxide dielectrics

Abstract

The integration of high-dielectric-constant (high-$\kappa$) materials with two-dimensional (2D) semiconductors is promising to overcome performance limitations and reach their full theoretical potential. Here we show that naturally occurring phlogopite mica, exfoliated into ultrathin flakes, can serve as a robust high-$\kappa$ dielectric layer for transition metal dichalcogenide-based 2D electronics and optoelectronics. Phlogopite's wide bandgap (~4.8 eV), high dielectric constant (~11), and large breakdown field (10 MVcm$^{-1}$) enable transistors with subthreshold swings down to 100 mVdec$^{-1}$, minimal hysteresis (30-60 mV) and interface trap densities comparable to state-of-the-art oxide dielectrics. Moreover, phototransistors built upon monolayer molybdenum disulfide (MoS$_2$) and phlogopite exhibit responsivities up to 3.3x10$^{4}$ AW$^{-1}$ and detectivities near 10$^{10}$ Jones, surpassing devices based on conventional gate insulators. We further demonstrate the versatility of this natural dielectric by integrating phlogopite/MoS$_2$ heterostructures into NMOS inverters, showcasing robust voltage gains and low-voltage operation. Our findings establish phlogopite as a promising, earth-abundant dielectric for next-generation 2D transistor technologies and high-performance photodetection.