Improved Thermal\nDissipation in a MoS<sub>2</sub> Field-Effect\nTransistor by Hybrid High‑<i>k</i> Dielectric Layers

Transition metal dichalcogenides like MoS<sub>2</sub> have been\nconsidered as crucial channel materials beyond silicon to continuously\nadvance transistor scaling down owing to their two-dimensional structure\nand exceptional electrical properties. However, the undesirable interface\nmorphology and vibrational phonon frequency mismatch between MoS<sub>2</sub> and the dielectric layer induce low thermal boundary conductance,\nresulting in overheating issues and impeding electrical performance\nimprovement in the MoS<sub>2</sub> field-effect transistors. Here,\nwe employed hybrid high-<i>k</i> dielectric layers of Al<sub>2</sub>O<sub>3</sub>/HfO<sub>2</sub> to simultaneously reduce the\ninterfacial thermal resistance and improve device electrical performance.\nThe enhanced contact, greater vibrational phonon overlapping region,\nand stronger interfacial bonding force between the top Al<sub>2</sub>O<sub>3</sub> layer and MoS<sub>2</sub> promote the heat removal\nefficiency across the interface to the substrate. Under the same input\npower density, the temperature profile of the MoS<sub>2</sub> transistor\non the Al<sub>2</sub>O<sub>3</sub>/HfO<sub>2</sub> has been largely\nreduced compared to that of the device on HfO<sub>2</sub>, with a\nmaximum reduction of 49.5 °C. In addition, the field-effect mobility\nand current of MoS<sub>2</sub> devices on the Al<sub>2</sub>O<sub>3</sub>/HfO<sub>2</sub> high-<i>k</i> dielectric layers\nhave been significantly improved, attributed to the depressed electron\nscattering and trap states at the interface. The design of the hybrid\nhigh-<i>k</i> dielectric layers provides an efficient solution\nto simultaneously improve the thermal and electrical performance of\nthe two-dimensional devices.