A Strategic Approach for Enhanced p-Type Doping of WSe2 p-MOSFETs Using an Atomic Oxidation Process

Abstract

Doping allows precise tuning of the electronic properties in 2D materials, optimizing their performance for applications such as complementary metal-oxide-semiconductor (CMOS) technology. However, developing reliable p-type 2D semiconductors remains challenging due to intrinsic defects or unintentional n-type doping. This study presents robust p-type monolayer WSe2 field-effect transistors (FETs) using phase-engineered WSe2/WSeyOx building blocks created via an atomic oxidation process (AOP). The findings reveal that when bilayer WSe2 is exposed to AOP, the top layer undergoes self-limited oxidation to WSeyOx with no detectable oxidation of the bottom layer. This result is confirmed by Raman spectroscopy, X-ray photoelectron spectroscopy, and Kelvin probe force microscopy. This process has further been used to demonstrate a well-controlled and fully encapsulated WSeyOx/WSe2/WSeyOx heterostructure, ensuring symmetrical protection and stability of the WSe2 channel region. The surface charge transfer doping using WSeyOx provides the capability to selectively modulate the carrier concentration in a WSe2 without altering the intrinsic properties of the channel. This non-destructive method simplifies the fabrication of p-type 2D FETs with monolithic, phase-engineered heterostructures, facilitating seamless integration into next-generation device architectures.