Persistent and reliable electrical properties of ReS2 FETs using PMMA encapsulation

We investigated electrical properties f ReS2 field effect transistor (FET) by focusing on how the absorbent molecules on the surface of ReS2 channel could affect to its FET performances. A few layer ReS2 based FET devices were fabricated by nanofabrication processes including micro-contact transfer method and electron-beam lithography technique. The FET characteristics were measured under following conditions: 1) with pristine device, 2) at vacuum condition, 3) after baking FET with hot plate, and 4) after PMMA spin-coating on FET. The current value at output characteristics were increased and hysteresis at transfer curve reduced when FET was measured in vacuum state and after baking process. The improved FET performances such as higher current and mobility values after baking process could be maintained by encapsulating the ReS2 channel using PMMA spin-coating process. The effects of absorbents such as water and oxygen molecules on the ReS2 surface were suggested based on the experimental results. Our results showed that simple baking and spin-coating methods could improve the electrical characteristics and maintain a persistent performance of ReS2 FET.