Formation of various metal nanostructures with thermal annealing to control the effective coupling energy between a surface plasmon and an InGaN/GaN quantum well

Abstract

We demonstrate the variations of the photoluminescence (PL) spectral peak position and intensity through the surface plasmon (SP) coupling with an InGaN/GaN quantum well (QW) by forming Ag nanostructures of different scale sizes on the QW structure with thermal annealing. By transferring an Ag thin film into a nanoisland structure, we can not only enhance the PL intensity, but also adjust the SP dispersion relation and hence red-shift the effective QW emission wavelength. Such an emission spectrum control can be realized by initially coating Ag films of different thicknesses. Although the screening process of the quantum-confined Stark effect, which can result in PL spectrum blue-shift and intensity enhancement, also contributes to the variations of the emission behaviour, it is found that the SP-QW coupling process dominates in the observed phenomena.

Surface plasmon coupling dynamics in InGaN/GaN quantum-well structures and radiative efficiency improvement

“…However, it has been confirmed through IQE, time-resolved PL, and electroluminescence (EL) measurements, that an enhancement due to metal NPs based on this excitation and detection scheme can indeed be attributed to LSP-QW coupling131415161718192223. Nonetheless it is still required to exclude the contribution from the enhanced reflection of the excitation source due to Ag NPs as done in Ref.…”

“…The energy out-coupling of these SPP modes into photons was later demonstrated through photoluminescence (PL) enhancement1314. Randomly distributed metal nanoparticles (NPs) have also been investigated as a way to improve the recombination rate through exciton coupling with localized surface plasmon (LSP) modes151617181920. The advantage of LSP modes comes from fact that they do not require a phase-matching condition in order to radiate the stored energy21.…”

Surface plasmon coupled light-emitting diode: Experimental and numerical studies

“…The metal NPs can be fabricated through the thermal annealing of a thin metal film. 20,21) In this situation, the size and position of metal NP are randomly distributed. Regularly arranged metal NPs of uniform size can be fabricated through nanoimprint lithography, dry etching, and liftoff process.…”

Surface plasmon enhanced LEDs

“…NPs with the required sizes and heights can be produced by annealing at different temperatures and for different times on metal fi lms with different thicknesses, to achieve the best coupling effect with the light emitters. Yeh et al (2007) annealed three samples with initial fi lm thicknesses of 5 nm, 10 nm and 15 nm at 200 °C for 30 min and they observed that the size and heights of silver NPs were signifi cantly increased. Annealing enhances the photoluminescence intensity of the SP light emitters due to enhanced SP/QW coupling.…”