Visualizing correlation between carrier mobility and defect density in MoS2 FET

Transition metal dichalcogenides (TMDs) with only a few atoms thickness provide an excellent solution to scale down current semiconductor devices. Many studies have demonstrated that molybdenum disulfide (MoS2), a member of TMDs, is promising as a channel material to fabricate field-effect transistors (FETs). However, the carrier mobility in MoS2 FET is always far lower than the theoretical prediction. Although this poor performance can be attributed to the defects, it still lacks a quantitative analysis clarifying the correlation between carrier mobility and defect density. In this work, by using scanning tunneling microscopy, we directly counted the defects in MoS2 FETs with different carrier mobility. We found that vacancies and impurities equally contribute to carrier mobility and the total defect density induces a power-law decreasing tendency to the carrier mobility of MoS2 FET. Our current results directly prove that the reduction of point defects can exponentially improve the carrier mobility of FETs made by TMDs. Published under an exclusive license by AIP Publishing.

Automated summary

Transition metal dichalcogenides (TMDs), with only a few atoms thickness, are a potential solution for scaling down semiconductor devices. However, the carrier mobility in molybdenum disulfide (MoS2) field-effect transistors (FETs) is lower than expected due to defects. This study directly counts the defects in MoS2 FETs with varying carrier mobility and finds that both vacancies and impurities contribute to the decrease in carrier mobility.