Investigation of and Raman Modes of Few-Layer MoS2 on HfO2 Substrate
Recently the research work by Radisavljevic et al. shows that the mobilities of monolayer MoS2 transistors can be improved by employing a thin layer of hafnium oxide as top-gate dielectric. Dielectric screening has been successfully demonstrated to suppress the Coulomb interactions of charged impurities on the substrate. Therefore, we develop an alternative method of building a monolayer MoS2 transistor on HfO2 substrate. Owing to the low contrast of few-layer MoS2 flakes on thin HfO2 substrate, which makes the realization of such device configuration difficult. By utilizing the thickness dependence of in-plane and out-of-plane Raman modes of MoS2 flakes, and, respectively, we establish an efficient approach to improve the identification of MoS2 layers by Raman spectrum instead of AFM. Our investigation of and Raman modes of few-layer MoS2 on HfO2 substrate shows the significant difference from those on SiO2 substrate. The substrate effect of Raman spectrum as well as its further application will be discussed in this talk.
Reference: . Radisavljevic, et al., Nat. Nanotech. 6, 147 (2011)