Control of Charge Transport Properties in Molybdenum Diselenide Field-Effect Transistors for Enhanced Noise-Margin and Inverter Characteristics

Abstract

Ambipolar field-effect transistor (FET) capable of transporting both holes and electrons has the advantage of operating as both p-type and n-type with a single device depending on the voltage bias condition. Among transition metal dichalcogenides (TMDs), molybdenum diselenide (MoSe₂), which has ambipolar properties, exhibits n-type dominant electrical characteristics. As a result, a digital inverter implemented only using pristine MoSe₂ FETs exhibited asymmetric and limited output swing characteristics because of the difficulty in pull-up operation. Therefore, a method for improving the p-type characteristics of MoSe₂ is needed to implement a complementary metal–oxide–semiconductor (CMOS)-like digital inverter using only MoSe₂. In this study, an n-type dominant MoSe₂ FET was adjusted to have p-type dominant characteristics through annealing process. Raman spectroscopy was used to compare the transistor with previous studies. Statistical analysis showed that the charge transport behavior was reproduced in multiple devices. The p-type enhanced MoSe₂ FET was applied as a pull-up transistor of a digital inverter to present the practicality of the annealing process to improve the p-type characteristics of the MoSe₂ FET. Eventually, a more symmetrical output swing and improved noise margin were achieved compared to a digital inverter composed of only n-type dominant MoSe₂ FETs.