Investigation on surface-plasmon-enhanced light emission of InGaN/GaN multiple quantum wells

We demonstrate surface-plasmon (SP) enhanced light emission from InGaN/GaN near ultraviolet (NUV) multiple quantum wells (MQWs) using Ag thin films and nano-particles (NPs). Two types of Ag NP arrays are fabricated on the NUV-MQWs, one is fabricated on p-GaN layer with three different sizes of about 120, 160 and 240 nm formed by self-assembled process, while the other is embedded close to the MQWs. In addition, the influence of the surface plasmon polariton (SPP) and localized surface plasmon (LSP) in NUV-MQWs has been investigated by photoluminescence (PL) measurement. Both PL measurements and theoretical simulation results show that the NUV light would be extracted more effectively under LSP mode than that of SPP mode. The highest enhancement of PL intensity is increased by 324% for the sample with NPs embedded in etched p-GaN near the MQWs as compared with the bare MQWs, also is about 1.24 times higher than the MQW sample covered with Ag NPs on the surface, indicating strong surface scattering and SP coupling between Ag NPs and NUV-MQWs.