Manipulation of the electrical and memory device properties of monolayer MoS2 field-effect transistors by highly charged ion irradiation

Molybdenum disulfide (MoS2) is a semiconductor material that is a member of the family of the so-called 2Dmaterials. The properties of these materials undergo dramatic changes when their thickness is reduced from their bulk (3D) form to their monolayer (2D) form. MoS2 develops a direct bandgap of 1.8-1.9 eV (ref. 1) when its thickness is reduced to its monolayer limit. This offers opportunities for applications in opto-electronic devices, like e.g., field-effect-transistors (FETs). These 2D-FETs open new possibilities for further device miniaturization because of their ultimate thinness. Open challenges to date are non-sufficient doping techniques, Schottky barriers and structural defects either in the channel material or the underlying oxide. These defects can cause the occurrence of a hysteresis in the transfer characteristics of such 2D-FETs by capturing charge carriers and consequently shifting the transfer characteristics depending on the gate voltage sweep direction. This hysteresis can be utilized to realize ultrathin 2D-memory devices [2].