Atomically precise graphene etch stops for three dimensional integrated systems from two dimensional material heterostructures

Abstract

Atomically precise fabrication methods are critical for the development of next-generation technologies. For example, in nanoelectronics based on van der Waals heterostructures, where two-dimensional materials are stacked to form devices with nanometer thicknesses, a major challenge is patterning with atomic precision and individually addressing each molecular layer. Here we demonstrate an atomically thin graphene etch stop for patterning van der Waals heterostructures through the selective etch of two-dimensional materials with xenon difluoride gas. Graphene etch stops enable one-step patterning of sophisticated devices from heterostructures by accessing buried layers and forming one-dimensional contacts. Graphene transistors with fluorinated graphene contacts show a room temperature mobility of 40,000 cm2 V−1 s−1 at carrier density of 4 × 1012 cm−2 and contact resistivity of 80 Ω·μm. We demonstrate the versatility of graphene etch stops with three-dimensionally integrated nanoelectronics with multiple active layers and nanoelectromechanical devices with performance comparable to the state-of-the-art.

Two‐dimensional heterostructure promoted infrared photodetection devices

“…E, Schematic of the XeF 2 etching process for a vdW heterostructure of stacked hBN and graphene layers. Reproduced with permission . Copyright 2018, Nature Publishing Group.…”

“…Designing new architectures or exploring new fabrication techniques to realize more precise and improved IR photodetection, have attracted many scientists . Son et al discovered a fabrication method to build integrated 3D electronic and optoelectronic 2DHs with graphene stops that consisted of graphene/fluorographene heterostructures (shown in Figure E). Researchers obtained an outstanding room temperature mobility of ~40 000 cm 2 V −1 second −1 and a low contact resistivity of ~80 Ω·μm.…”

“…Reproduced with permission. 77 Copyright 2018, Nature Publishing Group. F, Schematic design of the MoS 2 /graphene heterostructures based sensor array.…”

Extraordinary magnetoresistance in encapsulated monolayer graphene devices

“…These sensitivities exceed those of Hall sensors based on encapsulated graphene devices 21 . We note that encapsulated graphene devices are a technology that is still improving rapidly, with recent advances in limiting the role of scattering by using nearby graphite gates 22 , and implementing 2D contacts by XeF 2 etching of the hBN layers 23 which may greatly reduce the contact resistance and improve contact reproducibility. Neither approach is employed in the present study, suggesting that further improvements in device performance are achievable.…”

Etching Techniques in 2D Materials

“…Graphene often acts as a mask when the materials are etched by XeF 2 gas because graphene reacts with XeF 2 to form fluorographene which stops continuing the longitudinal etching. Son et al studied XeF 2 selective etching graphene/2D materials heterostructures . Figure a,b shows the schematic diagram and the optical microscopy images of the heterostructures before and after etching by XeF 2 gas.…”