Deciphering Vacancy Defect Evolution of 2D MoS2 for Reliable Transistors

Two-dimensional(2D) MoS2 is an excellent candidatechannel material for next-generation integrated circuit (IC) transistors.However, the reliability of MoS2 is of great concern dueto the serious threat of vacancy defects, such as sulfur vacancies(V-S). Evaluating the impact of vacancy defects on the servicereliability of MoS2 transistors is crucial, but it hasalways been limited by the difficulty in systematically tracking andanalyzing the changes and effects of vacancy defects in the serviceenvironment. Here, a simulated initiator is established for decipheringthe evolution of vacancy defects in MoS2 and their influenceon the reliability of transistors. The results indicate that V-S below 1.3% are isolated by slow enrichment during initiation.Over 1.3% of V-S tend to enrich in pairs and over 3.5% ofthe enriched V-S easily evolve into nanopores. The enrichedV(S) with electron doping in the channel cause the thresholdvoltage (V-th) negative drift approaching 6 V, while theexpanded nanopores initiate the V-th roll-off and punch-throughof transistors. Finally, sulfur steam deposition has been proposedto constrain V-S enrichment, and reliable MoS2 transistors are constructed. Our research provides a new methodfor deciphering and identifying the impact of defects.