Stable and Reversible Triphenylphosphine-Based n-Type Doping Technique for Molybdenum Disulfide (MoS).

A highly stable and reversible n-type doping technique for molybdenum disulfide (MoS) transistors and photodetectors is developed in this study. This doping technique is based on triphenylphosphine (PPh) and significantly improves the performance of MoS transistor and photodetector devices in terms of the on/off-current ratio (8.72 × 10 → 8.70 × 10), mobility (12.1 → 241 cm/V·s), and photoresponsivity ( R) (2.77 × 10 → 3.92 × 10 A/W). The range of doping concentrations is broadly distributed between 1.56 × 10 and 9.75 × 10 cm and is easily controlled by adjusting the temperature at which the PPh layer is formed. In addition, this doping technique provides two interesting properties that have not been reported for previous molecular doping techniques: (i) high stability leading to small variations in device performance after exposure to air for 14 days (on-current: 1.34% and photoresponsivity: 1.58%) and (ii) reversibility enabling the repetitive formation and removal of PPh molecules (doping and dedoping).