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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 (Δ k = 1 1 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. [ABSTRACT FROM AUTHOR]

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 350C, 450C and 550C for 6h. 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. [ABSTRACT FROM AUTHOR]

This work explores the structural, surface and optical properties of NiO films grown on Si, GaAs, PET and glass substrates. The NiO films were deposited on these substrates under same conditions by using radiofrequency (RF) magnetron sputtering of NiO target at 100C. The structural study by X-ray diffraction (XRD) showed the existence of (200) and (220) oriented NiO peaks on all the substrates. The preferred orientation of NiO films on Si, GaAs and glass was along (200) plane whereas the film grown on PET was observed to be oriented along (220) plane. The crystallite size of NiO on GaAs was the largest among the other substrates. The RMS surface roughness on PET was higher as compared to the other substrates. The band gap of NiO films grown on glass and PET was estimated from UV-Vis transmittance spectroscopy whereas the UV-Vis reflection spectroscopy was carried out to find out the band gap of NiO grown on GaAs and Si substrates. The band gap of NiO on PET was higher than its band gap obtained on other substrates. The results obtained on properties of NiO films on different substrates were correlated with each other. [ABSTRACT FROM AUTHOR]

This work presents the influence of changing Ar:N2 gas ratio on the growth and properties of InAlN films. InAlN films were deposited on -type Si(111) substrates by using magnetron co-sputtering method in 6:12, 10:10, 12:8 and 12:6 Ar:N2 mixtures at 300C. The surface, structural, electrical and optical properties of the deposited films were evaluated at different Ar:N2 ratios. The grain size and film thickness were increased by increasing the Ar flow with respect to N2. Structural characterization by X-ray diffraction (XRD) revealed an improvement in the crystalline quality of the -axis-oriented InAlN film by adjusting the Ar:N2 ratio to 12:8, however no diffraction peak corresponding to InAlN was detected at 6:12 Ar:N2 mixture. The surface roughness of InAlN film exhibited an increasing trend whereas the electrical resistivity of the film was decreased by increasing the Ar:N2 ratio. The bandgap of InAlN film was calculated from the optical reflectance spectra and it was found to change by changing the Ar:N2 gas ratio. The analysis of results from this work shows that the InAlN film with improved physical properties can be obtained through reactive magnetron co-sputtering method by adjusting the Ar:N2mixture to 12:8. [ABSTRACT FROM AUTHOR]

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 400C, 600C and 800C in nitrogen (N2) environment for 6h. 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 400C, yet the roughness increased when the annealing temperature is further increased to 800C. [ABSTRACT FROM AUTHOR]

This work investigates the growth of AlInN films on Si (100) substrates through the annealing of Al and InN stacking layers in the temperature range 200C to 800C. The Al/InN layers were prepared on Si (100) substrates using RF magnetron sputtering technique at 100C. The layers were annealed in a quartz tube furnace at 200C, 400C, 600C and 800C for six hours. Structural features of the films were examined through XRD whereas the surface morphology and composition of the films were studied through FESEM and EDS, respectively. The FESEM and EDS cross-sectional analyses of the films were also conducted to observe the mixing of Al/InN stacking layers. XRD patterns revealed the formation of polycrystalline AlInN films whereas the FESEM and EDS cross-sectional results indicated that the mixing of Al/InN stacked layers became more prominent with increase of the annealing temperature. Surface roughness of the films studied through AFM also exhibited an increasing trend with increase of the annealing temperature. [ABSTRACT FROM AUTHOR]

In this work, pure indium and aluminum targets were co-sputtered in a reactive argon-nitrogen environment at 200°C to deposit film on the substrate in the presence of a buffer layer. The as-grown film was annealed at 750°C for 1 h in a high temperature furnace under nitrogen ambient. XRD pattern of the as-grown film did not display any diffraction peak relating to the due to its poor structural crystallinity, however, the annealed film exhibited diffraction peaks corresponding to (002), (101) and (102) planes. A significant increase in the grain size and the surface roughness was observed after the films' annealing. Raman spectroscopy revealed A1 (LO) and E2 (high) phonon modes whereas the PL analysis showed a luminescence peak at 2 eV in the annealed film. The Hall measurements indicated an increase in the carrier concentration and electron mobility after the annealing which was accompanied by a decrease in electrical resistivity of the film. The dark current-voltage (I-V) characteristics of the as-grown and the annealed films were also recorded to investigate the barrier height and the ideality factor. [ABSTRACT FROM AUTHOR]