Large variability of contact resistance in Au/Cr/MoS2 system and its suppression by Cr thinning

Owing to the atomically small thickness and moderate bandgap of MoS2, the compound is expected to be a channel material for future short-channel and low-leakage transistors. However, the high contact resistance between a metal and MoS2 is a serious issue. Although many studies have been conducted to reduce contact resistance, the variability of contact resistance has not been investigated. In this study, we fabricated MoS2 transistors and evaluated their electrical properties. A large discrepancy in electrical characteristics, which originates from contact resistance variability was observed. We found that the contact resistance variability is due to the peeling of a metal from MoS2, which originates from the weak cohesion of the metal to MoS2 and the thermal contraction of the metal. To reduce thermal contraction, a thin contact metal is utilized. As a result, better adhesion of the metal and suppression of contact resistance variability are observed, which indicates that the reduction in the thermal contraction of metals is important to reduce contact resistance and its variability. (C) 2016 The Japan Society of Applied Physics