Research on a Patterned Sapphire Substrate for GaN-Based LED and the Fabrication by Wet Etching

In recent years, Patterned Sapphire Substrate (PSS) has become a research hotspot of GaN-based Light Emitting Diode (LED), for the two significant advantages this technology has embraced:it can not only reduce the defects and dislocation density of GaN epitaxial film, but also significantly improve the Light Extraction Efficiency (LEE) of LED. In this paper, a type of PSS and the corresponding manufacturing method are introduced, the cost could stay low with the wet etching, and good uniformity could also be achieved; by using our independent-designed etching system and the sulfuric acid - orthophosphoric acid mixture, a patterned structure with high duty ratio is obtained under the temperature of 280℃ after the etching duration of 40 minutes, and the etching depth is more than 2 μm; The main factors effecting on the etching rate such as duration, temperature and etching depth are also analyzed in this paper.