The Adhesion of Mica Nanolayers on a Silicon Substrate in Air

Abstract

properties render MNLs as a nearly perfect dielectric material that is expected to considerably improve the electron transport properties of Si based microelectronic devices. Previous studies demonstrated that the use of a MNL as the dielectric layer onto a Si substrate doubled the carrier mobility of graphene field effect transistors (FETs) and increased their transconductance several fold. [3] It also improves the gate control capability of carbon nanotubes (CNTs) FETs by suppressing gate leakage current and decreasing subthreshold slope. [4] In particular, MNLs can replace polymers as dielectric media in flexible electronics. [5,6] Compared with polymer insulators, MNLs not only improve the electron transport properties (because of their higher dielectric constant), but also reduce the effect of elastic mismatch because mica and Si have similar mechanical properties. [7] These make MNLs potentially excellent candidates for Si based flexible devices as dielectric components. In most electronic devices, an MNL is mechanically bonded onto a Si substrate. Thus, the adhesion between the MNL and Si substrate determines the reliability and life of the electronic devices. [8] This is especially important for flexible electronic devices with MNLs that frequently experience bending, twisting and stretching. [9] Characterization of the adhesion of MNLs on a flat substrate is challenging. Previous studies often used the atomic force microscopes (AFM) to measure the adhesion. [10] AFM directly measures the adhesive force of a target material with the AFM tip, rather than the adhesion energy that characterizes the adhesion. To evaluate the adhesion energy of graphene on a flat substrate, a blister method was used. [11] However, the sample preparation in the blister method is relatively long, which is not applicable for MNLs because they can be heavily contaminated during a lengthy preparation process. In situ scanning electron microscope (SEM) peeling is a possible alternative, but electron beam irradiation could considerably affect the surface status of MNL samples. [12,13] The peeling method is also inconvenient for characterising the effect of environmental conditions, such as temperature and humidity, on the adhesion that is the important knowledge for MNL based sensor design and development. [14] In our previous work, [15] a bridging method was developed based on nanomanipulation under an optical microscope, with Mica nanolayers (MNL) are a new dielectric material that can improve the electron transport properties of Si based microelectronic devices. However, the mechanical reliability of such devices is not well understood because measurement of the adhesion between an MNL and a Si substrate is insufficiently accurate. The recent work reports a bridging method that is developed based on the linear beam theory and can characterize the adhesion of MNL on a mica substrate in a reasonably accuracy. In this work, the accuracy of the bridging method is improved by using a nonlinear mechanical model. 15 MNL specimens are mea...

The adhesion of a mica nanolayer on a single-layer graphene supported by SiO2 substrate characterised in air

“…It is seen in figure 3(c) that the average adhesion energy between the MNL and Si substrate is 103.6± 10.3 mJ m −2 (dash dot line). This value is close to the adhesion of 110.7±19.4 mJ m −2 (dash line), measured by the bridging method [47]. This demonstrates that the improved Obreimoff method can provide a reliable measurement on the adhesion energy at microscale.…”

Frictional behavior of one-dimensional materials: an experimental perspective

“…The tendency of the 1D material to conform is dictated by the balance between the interfacial adhesion energy (the driving force for conformation) and the elastic energy associated with deection of the 1D material (the resistance to conformation). [127][128][129][130][131] The tendency of a 1D material to conform or not conform during sliding can lead to a non-constant friction force with respect to time, revealing distinctive frictional behavior. 125,132,133 The ease at which a 1D material can conform can also give rise to novel "electro-capillary-elastic" coupling behavior, deviating from the conventional theory that frictional forces originate from electrostatic and capillary forces alone.…”