Influence of AlN Thin Film as Thermal Interface Material on Thermal and Optical Properties of High-Power LED

An AlN thin film was fabricated and used as a thermal interface material (TIM) for a high-power light-emitting diode (LED) application. The AlN thin film was stacked with an Al thin film on Al substrates and used as a heat sink. The thermal behavior of a 3-W green LED mounted on the AlN and AlN/Al stack thin-film-coated substrates was tested using a dual interface method. A low value in junction temperature (T_J) of the LED was observed with an AlN/Al stack used as the interface. The observed total thermal resistance (R_th-tot) was low for the AlN/Al-stack-coated Al substrates compared to the bare and thermal-paste-applied Al substrates. The interface thermal resistance (R_th-b-hs) was influenced by the driving currents and observed a low value with the AlN-based coatings. Improved luminosity was observed from the LED with the AlN/Al stack as the TIM. The observed correlated color temperature (CCT) was low for the AlN/Al stack at all driving currents. No significant change was observed in the color rendering index (CRI) and peak wavelength (λ_peak).