2D Material Fabrication Strategies for The Study of Doubly Charged Exciton Complexes

Room temperature superconductivity has been a longstanding goal for the condensed matter community over the last half-century. A novel way of pursuing this is to create excitons bound to two extra charges, which form charged bosons. This type of system has been theoretically proposed to form a superconductor through the Schafroth superconductivity mechanism. In our most recent work, we have shown the existence of this type of charged exciton complex, which can be called a quaternion. This is made possible by placing a bilayer transition metal dichalcogenide heterostructure on a metal back gate to screen out the repulsive forces between the additional charges. Through electrical measurements, we have confirmed that it is composed of a free-charge carrier in the top layer bound to a like-charged intralayer Trion in the bottom layer. We will first discuss the different gating strategies we have developed to isolate and maximize the density of quaternions in comparison to other excitonic complexes. Then we will discuss how different heterostructure fabrication techniques affect the quality and size of viable regions that allow for quaternion formation.