RETRACTED: Cross- and in-plane thermal conductivity of AlN thin films measured using differential 3-omega method

Manuel Bogner,Gunther Benstetter,Yong Qing Fu

doi:10.1016/j.surfcoat.2017.01.100

Manuel Bogner, Gunther Benstetter + Show 1 more

Open Access

https://doi.org/10.1016/j.surfcoat.2017.01.100

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Journal: Surface Technology	Publication Date: Jan 27, 2017
Citations: 18	License type: cc-by

Affiliation: Northumbria University

Abstract

Thickness dependency and interfacial structure effects on thermal properties of AlN thin films were systematically investigated by characterizing cross-plane and in-plane thermal conductivities, crystal structures, chemical compositions, surface morphologies and interfacial structures using an extended differential 3ω method, X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy, atomic force microscopy (AFM) and transmission electron microscopy. AlN thin films with various thicknesses from 100 to 1000 nm were deposited on p-type doped silicon substrates using a radio frequency reactive magnetron sputtering process. Results revealed that both the cross- and in-plane thermal conductivities of the AlN thin films were significantly smaller than those of the AlN in a bulk form. The thermal conductivities of the AlN thin films were strongly dependent on the film thickness, in both the cross- and in-plane directions. Both the XRD and AFM results indicated that the grain size significantly affected the thermal conductivity of the films due to the scattering effects from the grain boundary.

Highlights

Aluminum nitride (AlN) thin films have been widely used in surface acoustic wave devices [1,2], light emitting diodes [3], and micro-electromechanical systems because of their outstanding properties, such as high piezoelectric coupling factor, excellent dielectric properties, wide band-gap, and high thermal conductivity
The experimental results have shown that both cross- and in-plane thermal conductivities of the AlN thin films are significantly reduced compared to that of their bulk material counterparts
The X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM) results indicated that the grain size of sputtered AlN films increases with the increase in film thickness

Summary

Introduction

Aluminum nitride (AlN) thin films have been widely used in surface acoustic wave devices [1,2], light emitting diodes [3], and micro-electromechanical systems because of their outstanding properties, such as high piezoelectric coupling factor, excellent dielectric properties, wide band-gap, and high thermal conductivity. Many thin films prepared using deposition technologies have many impurities, dislocations, and grain boundaries, all of which tend to reduce the thermal conductivity of the films [6,8,11]. Even though the film with less defects can be prepared, it is still expected to have reduced thermal conductivity due to grain boundary scattering and phonon leakage in the thin film materials. These two effects affect crossplane and in-plane heat transport differently, so that the thermal conductivities of the thin films are generally anisotropic in these two directions, even though their bulk counterparts have the isotropic properties. Higher accuracy and better reproducibility of the film's thermal conductivity data can be obtained

Experimental

Results and discussion

Conclusion