Two-dimensional (2D) electron systems represent one of the most important developments in solid-state physics, both from the fundamental and the applications point of view. A two-dimensional electron gas (2DEG) is a system where carriers are free to move in two dimensions, but are tightly confined in the third. To date, 2DEGs have been practically realized in metal–insulator–semiconductor (MIS) devices biased above the inversion threshold (Vth), in semiconductor heterojunctions (eg, AlGaAs/GaAs, AlGaN/GaN [1], etc.), in complex oxide interfaces (eg, LaAlO3/SrTiO3)[2], and, more recently, in graphene and other two-dimensional materials [3], such as the transition metal dichalcogenides (TMDs)(MoS2, WS2, MoSe2, WSe2, etc.) and Xenes (silicene, phosporene, etc.). The general criterion to observe a 2DEG behavior is that the electrons system is confined within a thickness t< 𝜆F, where 𝜆F= 2𝜋/kF≈ 2𝜋1/2/n1 …