Micro repeating structure using etching and repeating silica crystal structure growth to improve LED light extraction efficiency

Abstract

Light extraction efficiency (LEE) is a very important factor for improvement in efficiency by Light Emitting Diodes (LED). As of now, most LEE improvement methods involve complex fabrication either on the finished LED chip or during the LED processing. In this study micro repeating structures (MRS) are fabricated using both etching and silica mesoporous thin film growth (SMTFG) to improve LEE. In contrast to other complex fabrication methods, the SMTFG and etching were employed after roughened and un-roughened LED was produced. The SMTFG growth method was relatively simple, using tetraethyl orthosilicate (TEOS), surfactant and solvents while the etching method employed only sodium hydroxide (NaOH). The LEE result by SMTFG showed an average of 0.6% increment in brightness for un-roughened LED. However, negative results were observed for roughened LED with 0.7% reduction in brightness. On the other hand, by using short etching time at 30 seconds for cleaning the LED surface from contaminants with NaOH, the ...