Controllable p-Type Doping of 2D WSe ₂ pFET by Engineered Surface Charge Transfer Doping With Metal Co-Seeding

Surface charge transfer doping (SCTD) has emerged as a promising technique for doping 2D semiconductors, although it faces challenges in doping controllability, which impacts device performance. In this study, we introduce a novel approach to precisely control the p-type doping strength in solid-state SCTD for 2D WSe₂ field-effect transistors (FET) through metal <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">co-seeding</i>. By sequentially depositing molybdenum (Mo) and hafnium (Hf) metal seeds followed by O₂ annealing, we achieve improved doping control, while maintaining a high on/off current ratio. High-resolution transmission electron microscopy (HRTEM) images confirm the proposed co-seeding concept. This technique addresses doping controllability limitations in SCTD, enhances gate tunability, and it is viable for very-large-scale integration (VLSI) applications.