Thermal resistances of crystalline and amorphous few-layer oxide thin films

Liang Chen,Yu Hou,Niru Kumari

doi:10.1063/1.5007299

Liang Chen, Yu Hou + Show 1 more

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https://doi.org/10.1063/1.5007299

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Abstract

Thermal insulation at nanoscale is of crucial importance for non-volatile memory devices such as phase change memory and memristors. We perform non-equilibrium molecular dynamics simulations to study the effects of interface materials and structures on thermal transport across the few-layer dielectric nanostructures. The thermal resistance across few-layer nanostructures and thermal boundary resistance at interfaces consisting of SiO2/HfO2, SiO2/ZrO2 or SiO2/Al2O3 are obtained for both the crystalline and amorphous structures. Based on the comparison temperature profiles and phonon density of states, we show that the thermal boundary resistances are much larger in crystalline few-layer oxides than the amorphous ones due to the mismatch of phonon density of state between distinct oxide layers. Compared with the bulk SiO2, the increase of thermal resistance across crystalline few-layer oxides results from the thermal boundary resistance while the increase of thermal resistance across amorphous few-layer oxides is attributed to the lower thermal conductivity of the amorphous thin films.

Highlights

Phase change memory[1,2] and memristors[3,4] are promising candidates for the generation of nonvolatile memory
The ultralow thermal conductivity of W/Al2O3 nanolaminates can be attributed to the large thermal boundary resistance (TBR) at the interfaces between W and Al2O3, which have a large difference in Debye temperature
Applications requiring electrical insulation as well as high thermal insulation may preclude the use of metallic materials, necessitating the study of the TBR at interfaces between dielectrics

Summary

Introduction

Phase change memory[1,2] and memristors[3,4] are promising candidates for the generation of nonvolatile memory. Due to the size effects and lower bulk thermal conductivity, the temperature profile in the 20Å crystalline HfO2 film has a much larger slope than crystalline SiO2. The interfaces between SiO2 and HfO2 introduce addition thermal resistance in the crystalline few-layer structures as indicated by the change in slope of the temperature profiles in Fig. 2 (a) and (b).

Results

Conclusion