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Purpose This paper aims to study the influence of the Cu-Al2O3 film-coated Cu substrate as a thermal interface material (TIM) on the thermal and optical behaviour of the light-emitting diode (LED) package and the annealing effect on the thermal and optical properties of the films. Design/methodology/approach A layer-stacking technique has been used to deposit the Cu-Al2O3 films by means of magnetron sputtering, and the annealing process was conducted on the synthesized films. Findings In this paper, it was found that the un-annealed Cu-Al2O3–coated Cu substrate exhibited low value of thermal resistance compared to the bare Cu substrate and to the results of previous works. Also the annealing effect does not have a significant impact on the changes of properties of the films. Research limitations/implications It is deduced that the increase of the Cu layer thickness can further improve the thermal properties of the deposited film, which can reduce the thermal resistance of the package in system-level analysis. Practical implications The paper suggested that the Cu-Al2O3–coated Cu substrate can be used as alternative TIM for the thermal management of the application of LEDs. Originality value In this paper, the Cu substrate has been used as the substrate for the Cu-Al2O3 films, as the Cu substrate has higher thermal conductivity compared to the Al substrate as shown in previous work.

Aluminum oxide (Al2O3) thin films with Al2O3 buffer layer were deposited on Si (100) and Si (111) substrates using RF magnetron sputtering of Al2O3 target in Ar atmosphere. The synthesized films were then annealed at the temperature of 400[Formula: see text]C, 600[Formula: see text]C and 800[Formula: see text]C in nitrogen (N2) environment for 6[Formula: see text]h. Structural properties and surface morphology are examined by using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscope (AFM). XRD analysis indicated that different orientation of Al2O3 were formed with different intensities due to increase in the annealing temperature. From FESEM cross-section analysis results, it is observed that the thickness of films were increased as the annealing temperature increased. EDX analysis shows that the concentration of aluminum and oxygen on both the Si substrates increased with the increase in annealing temperature. The surface roughness of the films were found to be decreased first when the annealing temperature is increased to 400[Formula: see text]C, yet the roughness increased when the annealing temperature is further increased to 800[Formula: see text]C.

Copper aluminium oxide (Cu–Al2O3) films were synthesized on Si(111) substrates through RF magnetron sputtering by using the layer stacking technique. Cu and Al2O3 targets were used to deposit Cu and Al2O3 thin films under Ar atmosphere, respectively and the deposited films were then annealed under N2 environment at 350[Formula: see text]C, 450[Formula: see text]C and 550[Formula: see text]C for 6[Formula: see text]h. The structural properties of the films were investigated by using X-ray diffraction (XRD) while the surface morphology and topography of the deposited films were examined through Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray (EDX) and Atomic Force Microscopy (AFM). XRD analysis revealed the existence of multiple phases of CuO, Al2O3 and CuAl2O4 in the deposited films on Si(111) substrates. As a result of the annealing effect, the peak intensities of CuO, Al2O3 and CuAl2O4 were found to be increased along with the shifting of peak positions. Williamson–Hall (WH) analysis was also implemented to analyze the structural properties such as crystallite size, stress, strain, and energy density. Based on the three models used in WH analysis, the changes in the crystallite size and strain of the films were indicated to be anomalous with the changes in the annealing temperature. Moreover, the strain of films was also showed to be changed from compressive strain into tensile strain. The FESEM results also indicated the formation of various surface morphologies under various annealing temperatures whereas EDX analysis showed an increased atomic percentage of Cu, Al, and O due to the effect of increase in annealing temperature. The AFM analysis showed that the surface roughness of the deposited films increased with the increase in the annealing temperature.

Layer stacking technique is incorporated in the deposition of copper aluminium oxide (Cu-Al2O3) thin films on Al substrate using RF magnetron sputtering. The Cu/Al2O3 stack is sputtered using Cu and Al2O3 target at ambient temperature and then annealed to yield the resultant Cu-Al2O3 films. The structural properties of the films are investigated through X-ray Diffraction (XRD) whereas the chemical structure of the films is studied using Fourier-transform infrared (FTIR). The thermal conductivity analyzer is used to evaluate the thermal properties of coated film on the Al substrate. XRD analysis revealed that the synthesized films are polycrystalline film composed mainly of CuAl2O4 phase along with Al2O3 and CuO phases. The thermal properties of Cu-Al2O3 coated Al substrates showed improvement in terms of thermal conductivity and diffusivity compared to bare Al substrate. The Cu-Al2O3 sample annealed at 400∘C exhibited a significant difference in thermal conductivity ([Formula: see text][Formula: see text]W/mK) compared to bare Al. The difference in thermal conductivity displayed by the annealed sample verified that TIMs did enhance the thermal path of entire substrate by allowing the heat to dissipate to surrounding environment more efficiently, thereby improving the heat dissipation system. From the results observed, it can be concluded that Cu-Al2O3 coated Al substrate can be made as alternative TIM in thermal management application.