Controlled Charge Polarity in WSe₂ Field-Effect Transistor Grown by Self-Flux Method

In 2D materials, tungsten diselenide (WSe₂) has great potential for optical and electronic devices. However, the quality of WSe₂ crystals, determined by defects and grain boundaries, currently restricts its performance in controlling carrier-transport properties. Consequently, the most significant issue achieves superior growth of WSe₂ crystals and appropriate metal contacts. Herein, a doping-free approach to manipulate the polarity of WSe₂ transistors by utilizing distinct metal contacts is presented. WSe₂ field-effect transistors are examined employing low- and high-work function metals. In these findings, a transition in polarity from n-type for In and Cr to p-type for Pd and Au is demonstrated, showcasing remarkably high on/off ratios (≈10⁷) and mobilities (≈117 cm² V⁻¹ s⁻¹) at room temperature. This straightforward polarity control technique can be further extended by utilizing contact architecture-based research in other 2D materials for future nano-electrical and optoelectronic devices.