Doping Methods and Their Influences on Two-dimensional Photoelectric Device Materials

Because of their small size, easy integration and excellent photoelectric properties, two-dimensional semiconductor materials, such as graphene, black phosphorus, and transition metal dichalcogenides, are good channel materials for miniaturized photoelectric devices. However, there are limitations in the application of two-dimensional semiconductor materials that remain to be resolved. These challenges include the "zero band gap" of graphene, the degradation of black phosphorus in water or oxygen, and the low intrinsic mobility of TMDCs. Additionally, barrier height needs to be adjusted in the process of device production. Hence, it is necessary to implement doping methods to adjust the two-dimensional semiconductor materials. By introducing impurity atoms, doping can influence carrier type, carrier concentration, band gap and stability of semiconductor materials. This paper reviewed recent researches on doping methods of two-dimensional photoelectric device materials, and how doping influences material structure and material performance. For the purpose of clarity, the methods were separated into two main categories based on location of the doped impurity atoms, either in the crystal lattice or on the material surface. Under each category, various doping methods were then introduced, including the vapor-phase transport method, the ion implantation method, the surface deposition method, and the chemical spin/drops method, and then the advantages and limitations of each method were discussed.