Effects of Double-Side Patterning for Enhancement of Light Extraction Efficiency in GaN-based LEDs.

K.J. Kim, H.K. Lee, G.M. Go, B.J. Kim, Y.H. Song, K. Kim, J-L Lee
Pohang University of Science and Technology (POSTECH), KR

Keywords: light extraction efficiency, GaN-based LEDs, double-side patterning

Summary:

We demonstrate the double-side patterned sapphire substrate (DSPSS) to improve the light extraction efficiency of GaN-based LEDs. The bottom side of PSS LED wafer was polished and patterned using conventional photolithography and dry etching. After fabrication of lateral LEDs, silver (Ag) reflector was deposited on bottom side of PSS LED wafer. The LEDs with double-side PSS shows 10% higher light output power compared to LEDs with normal PSS. The numerical analysis using Ray tracing method was also performed with changes of pattern size and gap.