2D Material Bubbles: Fabrication, Characterization, and Applications

Abstract

Gases, liquids, and solids trapped underneath 2D materials deform the atomically thin material into micro- and nano-bubbles. Bubbles can form spontaneously or in controlled manners. Direct and indirect methods were used to probe the chemical contents inside these bubbles. There are a vast number of combinations possible for the 2D materials and trapped matter that form the bubble, which makes these bubbles a versatile platform for exploring rich nanoscale phenomena. Bubbles are conducive for creating confined and pressurized environments to trap chemicals and induce chemical reactions at high temperature. Atomically thin 2D materials allow for the in situ transmission electron microscope (TEM) observation of these chemical reactions. Bubbles also alter the physical properties of the 2D materials due to the nonuniform strain fields they can generate. When 2D materials are supported by substrates, matter trapped at the interface can coalesce to form nano- and microscale bubbles. These bubbles often negatively impact the performance of 2D material devices as they impede charge/photon/phonon transport across the interface. The difficulties created by these bubbles spurred research to understand how they form, whether their formation can be controlled, and what kind of matter is trapped inside them. These 2D material bubbles have since been exploited for novel chemistry and physics because of their ability to pressurize the trapped matter and strain the confining 2D material. The fabrication, characterization, and applications of 2D material bubbles are summarized in this review. When 2D materials are supported by substrates, matter trapped at the interface can coalesce to form nano- and microscale bubbles. These bubbles often negatively impact the performance of 2D material devices as they impede charge/photon/phonon transport across the interface. The difficulties created by these bubbles spurred research to understand how they form, whether their formation can be controlled, and what kind of matter is trapped inside them. These 2D material bubbles have since been exploited for novel chemistry and physics because of their ability to pressurize the trapped matter and strain the confining 2D material. The fabrication, characterization, and applications of 2D material bubbles are summarized in this review. the adsorbed contamination that accumulates on surfaces when exposed to ambient conditions. the transition in the electronic structure of a material such that electrons hopping from the valence band to the conduction band require a change in momentum, typically from the electron–phonon interactions. the situation in which capillary forces from liquids are relatively large enough to cause elastic deformation in solid structures. the pressure differential across a curved interface or surface. the spontaneous thermodynamic process in which smaller particles diffuse into larger particles. the nonuniform strain distributions in 2D materials that affect the transport properties of the electrons, analogous to the effect a magnetic field applied perpendicularly to the graphene basal plane would have on those electrons. the attractive force between two bodies that varies with the separation of the two bodies in consideration. The forces that give rise to vdW bonding result from fluctuating dipole interactions between atoms that constitute the neighboring bodies.