Power Enhancement of 410-nm InGaN-Based Light-Emitting Diodes on Selectively Etched GaN/Sapphire Templates

Abstract

A selectively etched (SE) GaN template for highpower 410-nm InGaN-based LEDs was fabricated, where 2-mu m-thick undoped GaN was grown on recess patterned sapphire substrates (PSSs). This was followed by H(3)PO(4) selective etching, 0.5-mu m-thick SiO(2) film deposition, and a final chemical-mechanical polishing process to remove the excess SiO(2). Three kinds of substrates, i.e., conventional sapphire substrates (CSSs), recess PSSs, and SE GaN templates, were used to grow the near-UV LEDs for comparison. The etched pit density of n-type GaN could then be reduced to 10(5) cm(-2), whereas the number of screw-type and edge-type threading dislocations decreased by 16.5% and 49.9%, respectively, since SiO(2) fillings on the SE GaN template hindered their propagation. The output power of a near-UV LED fabricated on the SE GaN template was 13% and 46% higher than that of a near-UV LED fabricated on recess PSSs and CSSs, respectively. A substantial improvement in performance can be attributed to the improved epilayer crystallinity and, also, the increased light scattering within the LED induced by SiO(2) fillings.