Optical Modification of 2D Materials: Methods and Applications

Abstract

on the same chip, which is promising for integrated electronics or photonics applications, [7] such as lasers, [8][9][10] optical modulators, [11] and photodetectors. [12] Indeed, 2D materials are an excellent candidate for postsilicone electronics due to their unique properties, versatile scaling of channel length, reduced device dimensionalities, and the possibility of creating circuits nearly at the atomic level. [13] Currently, some of the biggest challenges for 2D material synthesis include the lack of large-scale manufacturing and the necessity of harsh or arduous microand nanofabrication methods. Typical fabrication methods are based on chemical vapor deposition (CVD) and mechanical exfoliation from bulk crystals. The former involves a process that results in layers with relatively high concentrations of atomic impurities, [14] and the latter is limited in producing large area flakes. [14] Further fabrication steps for the incorporation of 2D materials into integrated devices typically require processes like electron-beam lithography and reactive ion etching, [15] both of which can be harmful to flakes that are atomically thin.All-optical processing of 2D materials has been demonstrated to overcome limitations of the conventional synthesis methods. It is time-and cost-effective, and it is also a promising fabrication alternative over CVD and mechanical exfoliation. Optical modification processes offer selectivity, locality, directionality, tunability, less harmful conditions, and on-demand functionalities, such as optical doping, [16][17][18][19] oxidation, [20][21][22][23] optical thinning, [24][25][26][27][28] and phase change. [29][30][31][32] Additionally, almost all of the optical modification and fabrication methods can be used for laser-direct writing (LDW) of patterns and structures at the microscale. [33][34][35][36] The high precision of LDW is particularly advantageous in the evolving world of nanofabrication. Lasers allow local modification of 2D material electronic bandgap, [37] thickness, [25] strain, [33,[38][39][40] and chemical composition, [19,41,42] even beyond the diffraction limit. [33] The created structures and patterns can often be directly used for applications in sensors, [22] energyprocessing devices, [43] and holography [44] (Figure 1). All the major demonstrations using LDW on 2D materials are listed in Table 1. Here, we review the optically assisted synthesis and fabrication methods of 2D materials, and their state-of-theart applications, providing detailed descriptions and features of optically engineered devices using 2D materials. We have straightforwardly introduced light-matter interactions and 2D-material-light interactions, and we also present our perspectives on this emerging field.2D materials are under extensive research due to their remarkable properties suitable for various optoelectronic, photonic, and biological applications, yet their conventional fabrication methods are typically harsh and costineffective. Optical modification is demonstrated as an effective an...

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