| 초록 |
Transition metal dichalcogenides (TMD) have received great interest because of their interesting electrical, optoelectronic, and chemical properties. Yet, carrier mobility, one of the critical parameters in transistor performance, has been much lower than theoretical limit in the MoS2 field-effect transistors (FETs) or bulk values. One of the strategies to improve carrier mobility is the encapsulation of MoS2 channel in a high-k dielectric environment (such as HfO2 or Al2O3). However, the use of high-k dielectric encapsulation to enhance mobility is not established yet because the mobility of single or multilayer MoS2 FETs can be significantly lower in HfO2 top-gate devices than that in SiO2 bottom-gate devices. In this presentation, we report the effect of Al2O3 encapsulation on the performance of multilayer MoS2 and MoSe2 FETs in bottom-gate thin-film transistor (TFT) configuration with SiO2 gate dielectrics. We demonstrate that Al2O3 encapsulation is useful in improving the carrier mobility of TMD TFTs by comparing the device performance before and after Al2O3 encapsulation. We further investigate the origin of mobility enhancement in Al2O3-encapsulated TFTs by calculating intrinsic carrier mobility and contact resistance based on Y-function method. |
