| Light-emitting diode (LED) by the advantages of light stability, small heat loss, long life and so on, is widely used in traffic, military, plane display and daily life of people. Especially LED with white light can replace traditional lighting for its energy saving and environmental protection, which is widely recognized as a new generation of solid-state lighting power supply. As the basis of white LED, the light-emitting efficiency of GaN-QWs LED with blue light is noteworthiness. High efficiency and high power, are important targets in the research and development of LED with blue light. Limited by the material and technological level, there’s still room for improvement in quantum efficiency of blue LED. Therefore, there’s a very important value of research and application in how to improve the luminous efficiency of LED, design and manufacture of high brightness, high efficiency of LEDs.Take advantage of the SPs-QWs coupling to make a high enhancement of photoluminescence has tremendous potential, which can not only improve the internal quantum efficiency of LED, but also the light extraction efficiency. However, the luminescence of GaN-QWs is a complex process, built-in polarization field, the localization and migration of charged carriers, etc. plays a key role in photoluminescence. Effect mechanism of surface plasmon that generated by noble-metal nanoparticles in GaN-QWs is not simple, but contain many factors, notjust including the usually known that excitons recombination energy transfer to surface plasmons and far field radiation by coupling. Surface plasmons especially localized surface plasmons influence the thermodynamics of charged carriers in quantum wells, especially in the presence of component or potential fluctuation in quantum wells, what the effect will be with the coupling of charged carriers and surface plasmons are short of systematic analysis and research until nowadays.This paper around the use of localized surface plasmon that generated by silver nanoparticles in the enhancement of photoluminescence of GaN-QWs, to carry out lots of methods and mechanism researches, as alternative offer for the preparation of high efficiency and low heat loss of LED with blue light. The key for GaN-LED in the preparation of SPs-QWs coupling, the measurement and analysis in light-emitting enhancement of coupling, the mechanism of exciton composite in radiative recombination of GaN both in single quantum well and multiple quantum wells, and the experimental study and analysis in the localization of carriers and dynamics of them in Q Ws with the effect of localized surface plasmons.The main results of this paper are described as follows:(1) Preparation of Ag nanoparticles by means of cluster beam deposition system, by controlling the coverage rate, annealing time and temperature, to realize the quantitative control of the morphology. Studied the influence of near field coupling to the properties of Ag nanoparticle array with surface plasmon resonance, this paper discussed the method of realizing the surface plasmon resonance properties control.(2) Studied the effect in photoluminescence enhancement of the SPs-Q Ws coupling when there’s a spacer layer between Ag nanoparticles and quantum wells. Actually, established a set of atomic layer deposition system (ALD) to prepare GaN thin film, and established process parameters in the preparation of dielectric isolation spacer layer with methods of plasma enhanced chemical vapor deposition (PECVD) and atomic layer deposition (ALD).(3) Analyzed the influence of the surface plasmon resonance extinction spectra when different semiconductor dielectric spacer layer with silver nanoparticles coated. By selecting the morphology of Ag NPs and the parameters of dielectric spacer layer to achieve resonance coupling between Ag NPs of localized surface plasmon and dynamic of excitons in quantum wells, so as to get a great photoluminescence enhancement.(4) In view of the influence of multiple excitation and scattering in the study of SPs-QWs coupling, put forward two measurements and analysis methods:on the one hand, considering the extinction effect of scattering and absorption of Ag nanoparticles, through careful and self-consistent integral measurement, make a quantitative analysis for the influence factors of the measured PL intensity, in order to obtain the exact luminescence enhancement coefficient. On the other hand, through the measurement of temperature-dependent PL spectra, we make a normalization to each PL spectrum in low temperature (10K), where the nonradiative recombination negligible, which can figure out the net luminescence enhancement of LED at room temperature. Experiments show that, these two methods have good consistency.(5) Established a comprehensive experiment on quantitative measurement of the coupling of SPs-QWs, including multichannel measurement of PL with continuous laser excitation at room temperature, temperature-dependent PL with pulse laser and time-resolved photoluminescence (TRPL) synchronous measurement system. Get the light-emitting efficiency of practical enhancement factors of LSP-QWs coupling with Ag nanoparticles at room temperature. For the GaN based single quantum well, net enhancement ratio of PL intensity is 160%, compare with GaN based multi-quantum wells, net enhancement factors of PL intensity is up to 250% at room temperature.(6) Analyzed mechanism of free and bound excitons in QWs of the near band edge transitions of luminescence with the localized surface plasmon resonance of Ag nanoparticles, from the localized surface plasmon effect, PL peaks of GaN-quantum wells with Ag NPs-coated occurred blue shift when keeping the system "S-shift" characteristics of temperature variation, showed that the screen of quantum confined Stark effect in quantum well is stronger as coupling of localized surface plasmons with Ag nanoparticles, promoting the localization on carriers, effectively inhibit the luminescence redshift and radiation efficiency decreasing that caused by internal built polarization field in quantum wells, resulting in the enhancement of LED luminescence efficiency.(7) The analysis of temperature-dependent of PL and time-resolved photoluminescence (TRPL) of InGaN/GaN multiple quantum wells of not perfect growth, in order to understand deeply the internal mechanism of the enhancement of emission when surface plasmons coupled with quantum wells. Research shows that the existence of components or potential fluctuation in the quantum well (such as aggregated In-rich region, quantum dot-like), there will be a significant impact on the dynamics of carriers with localized surface plasmon, resulting in blue-shift of PL peaks with temperature related, associated relative change of luminescence intensity with InGaN near band edge transition and aggregated In-rich region and the extension of luminescence life. Proposed an integrated model of PL enhancement with localized surface plasmon coupling with quantum wells:laser radiated from the surface of the Ag nanoparticles plasmon localized field to promote the localization of excitons in quantum wells, and excitons recombination process can be further strengthening due to the coupling of excitons and surface plasmons, the combined effect of both makes photoluminescence greatly enhanced in quantum wells at room temperature.(8) The preparation of electrode on MQWs and have bias voltage applied on, study the effect of applied electric field on PL and TRPL in quantum wells, which showed that there’s equivalent on the effect of bias and the coupling of SPs-QWs, further validation of the role of localize field in QWs have localization on charged carriers.(9) Analyzed the effect of luminescence quenching and generation of photocurrent whenAg nanoparticles mixed with GaN based quantum wells. Experiments show that, when in direct contact with Ag nanoparticles and quantum well, there’s a significant effect in fluorescence quenching, weakening the coupling between surface plasmon and quantum, caused a decrease of PL. At the same time electrons transfer from quantum wells to Ag nanoparticles with quenching process, resulting in significant photocurrent in Ag nanoparticles.
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