Suspended Graphene Membranes with Attached Silicon Proof Masses as Piezoresistive Nanoelectromechanical Systems Accelerometers

Abstract

Graphene is an atomically thin material that features unique electrical and mechanical properties, which makes it an extremely promising material for future nanoelectromechanical systems (NEMS). Recently, basic NEMS accelerometer functionality has been demonstrated by utilizing piezoresistive graphene ribbons with suspended silicon proof masses. However, the proposed graphene ribbons have limitations regarding mechanical robustness, manufacturing yield, and the maximum measurement current that can be applied across the ribbons. Here, we report on suspended graphene membranes that are fully clamped at their circumference and have attached silicon proof masses. We demonstrate their utility as piezoresistive NEMS accelerometers, and they are found to be more robust, have longer life span and higher manufacturing yield, can withstand higher measurement currents, and are able to suspend larger silicon proof masses, as compared to the previous graphene ribbon devices. These findings are an important step toward bringing ultraminiaturized piezoresistive graphene NEMS closer toward deployment in emerging applications such as in wearable electronics, biomedical implants, and internet of things (IoT) devices.

Large-area integration of two-dimensional materials and their heterostructures by wafer bonding

“…The recent discovery of specific twist angles between two graphene layers that give rise to astonishing properties such as unconventional superconductivity, correlated insulation, and magnetism 24 – 26 has spurred great interest in new methods for well-controlled fabrication of double-layer graphene. Furthermore, the stacking of two or multiple layers of 2D materials is of interest for controlling the stiffness of nanoelectromechanical devices 78 , 79 .…”

Transition metal dichalcogenide metamaterials with atomic precision

“…We envision that the combination of high surface-to-volume ratio and exclusively zigzag edges, which arise in these TMD metamaterials, could be useful for multiple purposes, including TMD-based catalysis 6 , 7 and sensing 37 applications. Furthermore, there is a potential for other areas and applications, such as photodetectors 38 , quantum transport 4 , nonlinear optics 18 , nanophotonics 29 , and optomechanics 39 to benefit from the method. Finally, we speculate that it may be possible to generalize a modified version of this method to other 2D material classes, such as graphene, hexagonal boron nitride, Mxenes, and others, because the anisotropic etching mechanism is likely related to different relative stabilities of various edges and planes (zigzag, armchair, and basal), which is a generic property of any vdW material with hexagonal crystallographic symmetry.…”

Nanoelectromechanical Sensors Based on Suspended 2D Materials

“…Some of the issues can be avoided by either growing [ 131 , 132 ] or transferring unsuspended 2D materials directly on the device substrate [ 72 , 133 ] (Figures 1(c) – 1(e) ). It can then be patterned and subsequently the membrane can be released by isotropically underetching (Figures 1(h) and 1(i) ), by using a sacrificial layer [ 134 – 137 ] or by releasing the membranes from the backside ( Figure 1(j) ).…”

“…It can then be patterned and subsequently the membrane can be released by isotropically underetching (Figures 1(h) and 1(i) ), by using a sacrificial layer [ 134 – 137 ] or by releasing the membranes from the backside ( Figure 1(j) ). The remaining through-hole can be left open or resealed after release [ 133 , 138 ]. Process steps that avoid capillary forces during drying, such as CPD or hydrofluoric acid (HF) vapor etch, can be used to avoid stiction and increase the yield of intact suspended membranes.…”

“…To this end, device designs based on fully clamped membranes improve the mechanical robustness by avoiding edges that are starting points for tearing under stress. However, this approach is a compromise as the signal response of fully clamped membranes is generally lower than that of ribbons with identical proof masses and trench width due to the lower strain levels and parasitic parallel resistances [ 133 ].…”