Effect of substrate temperature deposition on the thermal and optical performance of ZnO thin films as thermal interface material

ZnO thin films were deposited onto aluminium substrates at different substrate temperatures from 300 to 450 °C by chemical vapour deposition method using zinc acetate dihydrate as precursor. The effects of substrate temperatures on the thermal and optical performances of a light emitting diode package were investigated. The thermal transients show that thin film deposited at 400 °C has the lowest thermal resistance and junction temperature with a different difference of 1.3421 K/W and 2.7 °C respectively. The correlated colour temperature of the LED interfaced with ZnO prepared at 400 °C showed a good agreement with the thermal performance and exhibited the lowest correlated colour temperature as the driving current increases. The luminance shows that bare Al demonstrate the lowest luminosity compare to the coated thin film as TIM. The excess heat that trapped within the air gaps affects the heat flow. This eventually affects the luminosity of the LED. Furthermore, the AFM measurements of CVD 3 (400 °C) samples show low roughness values which contribute to good thermal resistance and junction temperature values. Overall, the present study shows that the performance of the LED has been enhanced with ZnO thin film used as TIM.