Enhanced coupling efficiency and electrical property in surface plasmon-enhanced light-emitting diodes with the...

We design, fabricate and analyze plasmon-enhanced LEDs with the tapered Ag structure that significantly increases plasmonic coupling efficiency at a coupling distance far beyond the penetration depth. The electroluminescence intensity showed a 16-fold increase compared with planar LEDs with a coupling distance of 100 nm. The enhanced coupling efficiency with large distance is originated from the accumulated SP energy at the metal conical tip and the missing momentum provided by the corrugated surface. Therefore, the SP-enhanced LED with tapered Ag structure can maintain a high luminous efficiency and a stable working state even with thick p-GaN layer, which also guarantees a high electrical performance. Our study paves the way for a practical implementation of SP-enhanced LEDs with excellent optical and electrical properties.