Producing next-generation transistors through doping

Two-dimensional transition metal dichalcogenides, TMDs, have become immensely popular in the quest to produce faster, more energy-efficient computation. While these materials possess many favorable functionalities, such as magnetism, ferroelectricity, and band-structure modulation, important challenges to the advancement of TMD-based semiconductors still exist.

Younas et al. presented the advantages and limitations of several traditional and emerging doping methods for TMD transistors.

Because of their atomically thin bodies, desired bandgaps, stability, immunity to short channel effects, and possible integration with industry-compatible substrates, TMDs show promise for next-generation transistors. The search for 2D semiconductors, which started with graphene, has since expanded to hundreds of new materials, dopants, and their combinations. However, a lack of precise control over carrier concentration, electrical conductivity, and threshold voltages are issues that must be addressed.

“We investigated the various methods for doping TMDs to try to determine the solutions that have the most upside and solvable problems,” said author Christopher Hinkle.

The authors focused on electrostatic, surface-charge transfer, intercalation, substitutional, and several new doping methods. The evidence indicates that substitutional doping is the most promising method due to its scalability, thermal stability, and widely-available dopants.

“We hope that the research community will focus more on the substitutional doping of TMDs rather than methods that allow short-term device demonstrations but have fundamental flaws,” said Hinkle. “While there remain challenges with substitutional doping, these challenges can be overcome and do not limit their use compared with other doping methods.”

Source: “A perspective on the doping of transition metal dichalcogenides for ultra-scaled transistors: challenges and opportunities,” by Rehan Younas, Guanyu Zhou, and Christopher L. Hinkle, Applied Physics Letters (2023). The article can be accessed at https://doi.org/10.1063/5.0133064 .