Microelectronic devices have become an inseparable part of our everyday life. In order to keep up with the increasing demand in performance, the development of these essential building blocks is coordinated in the IRDS roadmap. Conventional silicon technology faces the challenge that the silicon channel is difficult to scale below 12nm, as then the mobility of silicon degrades considerably. The recent IRDS roadmap highlights the potential of two-dimensional (2D) materials for scaling electronic devices down to the atomic limit as these materials can maintain a decent mobility even in the monolayer form. The ultimate goal is to achieve ultra-densely packed and ultra-fast devices with ultra-low power consumption for nanoelectronic applications of the 2030s. Various challenges exist, including identification of the 2D material with the highest mobility, reduction of the contact resistances, various fabrication challenges, and the lack of a suitable insulator which is required for the fabrication of field effect transistors (FETs).
Compared to the other challenges, relatively little attention has been paid to the search of insulators compatible with 2D channel materials. We suggested that ionic compounds such as fluorides may offer advantages in device performance and stability. Following our demonstration of ultrathin calcium fluoride (CaF2) as an insulator for 2D FETs, the F2GO project aims to advance 2D nanoelectronics by using fluoride-based insulators for advanced devices, enabling technologies like ultra-scaled non-volatile memory and steep slope devices for CMOS logic.
In the F2GO project, various fluorides are explored for their use in 2D nanoelectronics, starting with CaF2 and SrF2. Contrary to the prototype devices, which used CaF2 epitaxially grown on Si(111) substrates, which resulted in undesired space charge regions in the Si substrate, F2GO investigates the growth of fluorides on metallic substrates (for contacts) and 2D channel materials (for top gates). Once suitable insulator films are available, devices will be fabricated, characterized and modeled. All experimental efforts will be supported by theoretical calculations, starting from the ab initio level up to TCAD. These theoretical efforts will guide the experiments by explaining the observations, provide suggestions for different materials based on predicted permittivities and bandgaps, and eventually lead to better quality devices.
