Improved Thermal Dissipation in a MoS2 Field-Effect Transistor by Hybrid High-k Dielectric Layers.

Abstract

Transition metal dichalcogenides like MoS₂ have been considered as crucial channel materials beyond silicon to continuously advance transistor scaling down owing to their two-dimensional structure and exceptional electrical properties. However, the undesirable interface morphology and vibrational phonon frequency mismatch between MoS₂ and the dielectric layer induce low thermal boundary conductance, resulting in overheating issues and impeding electrical performance improvement in the MoS₂ field-effect transistors. Here, we employed hybrid high-k dielectric layers of Al₂O₃/HfO₂ to simultaneously reduce the interfacial thermal resistance and improve device electrical performance. The enhanced contact, greater vibrational phonon overlapping region, and stronger interfacial bonding force between the top Al₂O₃ layer and MoS₂ promote the heat removal efficiency across the interface to the substrate. Under the same input power density, the temperature profile of the MoS₂ transistor on the Al₂O₃/HfO₂ has been largely reduced compared to that of the device on HfO₂, with a maximum reduction of 49.5 °C. In addition, the field-effect mobility and current of MoS₂ devices on the Al₂O₃/HfO₂ high-k dielectric layers have been significantly improved, attributed to the depressed electron scattering and trap states at the interface. The design of the hybrid high-k dielectric layers provides an efficient solution to simultaneously improve the thermal and electrical performance of the two-dimensional devices.