Low-Dimensional Liquid Metal Electronics

A variety of 2D materials (Ga2O3, In2O3, SnO, and GaN) have been shown to print directly on different substrates such as SiO2, Si, quartz, and plastics with the help of liquid metals, in ambient air and gas special atmospheres, chemical reagents, and even in combination with outfield assistance (Li et al., NPJ 2D Mater Appl 5:1-10, 2021). This type of printing represents a new model for rapid manufacturing of conventional or 2D semiconductors, with a wide range of materials and applications available. As some of the representative applications, this chapter introduces a series of technology cases that can be expected to be industrially applied, such as the use of liquid metal combined with gas-mediated preparation of centimeter-scale two-dimensional (2D) n-type gallium oxide and thus realize the fully printed ultraviolet photodetectors, such as through the liquid metal doping process to successfully prepare two-dimensional p-type gallium oxide and thus also realize the stability of the p-type FET, as well as through the introduction of plasma-triggered gallium metal preparation of gallium nitride in two dimensions, thereby realizing high-performance FETs, and so on. Through a series of characterization, the properties of printed 2D semiconductor films are quantified. Further, in order to explore and promote the advantages of this kind of 2D semiconductor in practical functional electronics applications, the strategy of developing fully printed 2D electronics through low temperature, large area, and low cost process is analyzed, and the characteristics of fully printed Ga2O3/Si heterojunction photodetectors are explained. This kind of method has a certain universality; by choosing different doping and material modification, it can also realize different frequency photoelectric converters such as X-ray detectors, photovoltaic cells, etc.; on the contrary, reasonably designed materials can also be used to print luminaries and displays such as micro-LED, etc. These technologies will bring major changes and significant energy-saving and emission reduction effects for industrial applications in related fields. Through these methods, it can be seen that almost all optoelectronic components can be expected to be directly deposited by printing liquid metals and related materials, and the annealing temperature allows manufacturing on commercial flexible substrates without additional auxiliary structures, and the corresponding devices have excellent sensitivity and fast light response time. These efforts provide a feasible way to develop inexpensive, large-area, high-performance, photoelectric converters suitable for personalized production and also provide a promising direction for the future large-scale manufacturing of optoelectronics and electronic systems.