Influence of Molar Concentration: Sol-Gel Synthesized Magnesium Oxide Thin Films for High Power Light Emitting Diode Thermal Management

Abstract

Sol-gel technique was used to synthesize 0.6 M and 0.8 M molar concentrations of magnesium oxide thin on aluminium substrate and enforced into heat spreader material in thermal management of lighting devices. X-ray diffraction analysis confirm the films to be polycrystalline cubic in nature with (200), (220) and (222) orientations. 20 layers from 0.8 M showed higher intensity from the X-ray analysis. Relative thermal conductivity measurement of 20 layers from 0.6 M showed a value of (26.3 W/mK) which appears to improve over other layers. At 700 mA operating current, 20 layers from 0.6 M showed higher junction temperature difference of 37.16 °C as well as higher thermal resistance difference of 5.9 K/W when compared to bare aluminium substrate. All coated films are within the accepted color correlated temperature safe operating range (< 3300 K) of light emitting diodes, addition to this, 20 layers MgO thin films from 0.6 M displayed a recommendable illuminance as well as color correlate temperature performance from optical characterization. Atomic force microscope surface analysis for both molar concentrations showed an improvement in surface smoothness over bare substrate. Overall, magnesium oxide thin films can be perfectly enforced as heat spreader for high power light emitting diodes.