Role of substrate quality on the performance of semipolar (11(2)over-bar2) InGaN light-emitting diodes

We compare the optical properties and device performance of unpackaged InGaN/GaN multiplequantum- well light-emitting diodes (LEDs) emitting at similar to 430 nm grown simultaneously on a highcost small-size bulk semipolar (11 (2) over bar2) GaN substrate (Bulk-GaN) and a low-cost large-size (11 (2) over bar2) GaN template created on patterned (10 (1) over bar2) r-plane sapphire substrate (PSS-GaN). The Bulk-GaN substrate has the threading dislocation density (TDD) of similar to 10(5) cm(-2) -10(6) cm(-2) and basal-plane stacking fault (BSF) density of 0 cm(-1), while the PSS-GaN substrate has the TDD of similar to 2 x 10(8) cm(-2) and BSF density of similar to 1 x 10(3) cm(-1). Despite an enhanced light extraction efficiency, the LED grown on PSS-GaN has two-times lower internal quantum efficiency than the LED grown on Bulk-GaN as determined by photoluminescence measurements. The LED grown on PSS-GaN substrate also has about two-times lower output power compared to the LED grown on Bulk-GaN substrate. This lower output power was attributed to the higher TDD and BSF density. Published by AIP Publishing.