Growth-substrate induced performance degradation in chemically synthesized monolayer MoS2ﾠfield effect transistors
We report on the electronic transport properties of single-layer thick chemical vapor deposition (CVD) grown molybdenum disulfide (MoS2) field-effect transistors (FETs) on Si/SiO2 substrates. MoS2 has been extensively investigated for the past two years as a potential semiconductor analogue to graphene. To date, MoS2 samples prepared via mechanical exfoliation have demonstrated field-effect mobility values which are significantly higher than that of CVD-grown MoS2. In this study, we will show that the intrinsic electronic performance of CVD-grown MoS2 is equal or superior to that of exfoliated material and has been possibly masked by a combination of interfacial contamination on the growth substrate and residual tensile strain resulting from the high-temperature growth process. We are able to quantify this strain in the as-grown material using pre- and post-transfer metrology and microscopy of the same crystals. Moreover, temperature-dependent electrical measurements made on as-grown and transferred MoS2 devices following an identical fabrication process demonstrate the improvement in field-effect mobility.