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

J Huang and YF Li and XT Yu and ZX Liu and FF Wang and Y Yue and R Zhang and RW Dai and K Yang and H Liu and QY Fan and DH Hong and Q Chen and ZQ Wang and Y Gao and GQ Xin, ACS APPLIED MATERIALS & INTERFACES, 16, 62527-62536 (2024).

DOI: 10.1021/acsami.4c12143

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 degrees 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.

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