title: Ultra-large suspended graphene as a highly elastic membrane for capacitive pressure sensors.
abstract: In this work, we fabricate ultra-large suspended graphene membranes, where stacks of a few layers of graphene could be suspended over a circular hole with a diameter of up to 1.5 mm, with a diameter to thickness aspect ratio of 3 × 10(5), which is the record for free-standing graphene membranes. The process is based on large crystalline graphene (∼55 μm) obtained using a chemical vapor deposition (CVD) method, followed by a gradual solvent replacement technique. Combining a hydrogen bubbling transfer approach with thermal annealing to reduce polymer residue results in an extremely clean surface, where the ultra-large suspended graphene retains the intrinsic features of graphene, including phonon response and an enhanced carrier mobility (200% higher than that of graphene on a substrate). The highly elastic mechanical properties of the graphene membrane are demonstrated, and the Q-factor under 2 MHz stimulation is measured to be 200-300. A graphene-based capacitive pressure sensor is fabricated, where it shows a linear response and a high sensitivity of 15.15 aF Pa(-1), which is 770% higher than that of frequently used silicon-based membranes. The reported approach is universal, which could be employed to fabricate other suspended 2D materials with macro-scale sizes on versatile support substrates, such as arrays of Si nano-pillars and deep trenches.
authors.affiliation: Graduate Institute of Energy Engineering, National Central University, Tao-Yuan 32001, Taiwan. cysu@ncu.edu.tw.
authors.forename: Yu-Min
authors.initials: YM
authors.lastname: Chen
authors.forename: Shih-Ming
authors.initials: SM
authors.lastname: He
authors.forename: Chi-Hsien
authors.initials: CH
authors.lastname: Huang
authors.forename: Cheng-Chun
authors.initials: CC
authors.lastname: Huang
authors.forename: Wen-Pin
authors.initials: WP
authors.lastname: Shih
authors.forename: Chun-Lin
authors.initials: CL
authors.lastname: Chu
authors.forename: Jing
authors.initials: J
authors.lastname: Kong
authors.forename: Ju
authors.initials: J
authors.lastname: Li
authors.forename: Ching-Yuan
authors.initials: CY
authors.lastname: Su