Modulation Doping: Engineering Interfacial Charge Transfer in 2D Electronic Devices

In the pursuit of next-generation electronics, two-dimensional (2D) semiconductors are poised to lead due to their inherent advantages in compactness and low power consumption. However, their widespread adoption is hampered by issues such as high contact resistance and inefficient doping techniques. In this study, we explore workfunction-mediated charge transfer, or modulation doping, as a promising strategy to overcome these challenges and achieve high-performance p-type 2D transistors. Our investigation focuses on type-III band alignment and examines 27 potential materials, including transition metal oxides, oxyhalides, and the compound RuCl₃, as dopants for channel materials like transition metal dichalcogenides (TMDs) and group-III nitrides. Using extensive first-principles density functional theory (DFT), we identify significant p-type doping capabilities in materials with high electron affinity, such as RuCl₃, MoO₃, and V₂O₅. These materials demonstrate the potential to considerably reduce contact resistance and improve channel mobility via efficient hole transfer, all without introducing detrimental defects. Additionally, we analyze various transistor geometries and propose promising material combinations, expanding the focus beyond traditional WSe₂ doping to include innovative options like hBN, AlN, GaN, and MoS₂. This comprehensive study provides a strategic roadmap for developing high-performance p-type monolayer transistors and advancing the field of 2D electronics.