Optical performance of high power LED on silver and nickel thin film coated aluminum substrates using sputtering process

Abstract

Silver and Nickel thin films were prepared by sputtering technique and used as thermal interface materials to effectively improve the optical properties of LEDs. Different driving currents were used to test the performance of LED and measure the parameters such as color correlated temperature (CCT), Color Rendering Index and luminance LUX. The CCT value was found to be high for Ag (50 nm) buffered Ni (400 nm) thin film at 100 mA, which was subsequently decreased as the driving current increased. The results also showed that the lux value of the LED increased significantly for Ni (400 nm) thin film coated Al substrate boundary condition compared to Ag thin film with low thickness (50 and 100 nm) at 700 mA. Atomic Force Microscopy analysis of the thin film showed that Ag (100 nm) buffered Ni (200 nm) has the highest roughness compared to the other thin film coating. In general, the observed results showed that the Ni thin film and Ag (50 nm) buffered with Ni (400 nm) thin film can be effectively used as solid thin film thermal interface material, given that they improve the performance of the LED package significantly.