Photoluminescence Study of Surface Plasmon Coupling Behaviors with an InGaN/GaN Quantum Well
Date Issued
2014
Date
2014
Author(s)
Shih, Pei-Ying
Abstract
The pump power dependent, continuous and time-resolved photoluminescence (PL) measurements at 10 and 300 K in the three regions on two single InGaN/GaN quantum well (QW) epitaxial structures with the GaN capping layer thicknesses at 15 and 120 nm are performed. Among the three regions, an Ag film and a random distribution of Ag nanoparticles (NPs) are fabricated on the GaN capping layers to form the Ag-film and Ag-NP regions for inducing surface plasmon polariton (SPP) and localized surface plasmon (LSP) couplings with the QW, respectively, and comparing their behaviors. The region without any metal structure is used as the control condition. Without a significant surface plasmon (SP) coupling effect on the 120-nm capping layer, the PL measurement leads to the results of inconsistent variation trends among the three regions. With significant SPP or LSP coupling on the 15-nm capping layer, the integrated PL intensities in the Ag-film and Ag-NP regions are enhanced with respect to that in the control region at either 10 or 300 K. The weak dependencies of intensity ratio on pump power in the Ag-film and Ag-NP regions at 10 K indicate that at this temperature, the SP coupling effect is weak and the enhancements are mainly caused by the increased reflections at the Ag/GaN interfaces. Also, the weak dependence of intensity ratio on pump power in the Ag-NP region at 300 K implies the essentially fixed LSP coupling strength as pump power increases. However, the increasing trend of intensity ratio with pump power in the Ag-film region at 300 K shows that the SPP coupling strength can increase with the carrier density in the QW. This observation is confirmed by the larger increasing slope of internal quantum efficiency (IQE) and the steeper decrease of PL decay time with pump power in the Ag-film region. The increasing trend of the SPP coupling strength with pump power can be attributed to the screening of the quantum-confined Stark effect, which can blue-shift the QW emission wavelength for the QW to interact with the SPP of a higher density of state.
Subjects
光致螢光
表面電漿
氮化銦鎵
氮化鎵
量子井
Type
thesis
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