利用沉積與合成方式形成金屬奈米顆粒之表面電漿子耦合來增強基於量子點的光色轉換效率

Abstract

在本篇研究中，我們製備了五種金屬奈米顆粒，一種為表面沉積金屬奈米顆粒，另外四種為化學合成金屬奈米顆粒，我們將金屬奈米顆粒與紅光量子點放置於氮化鎵或氮化銦鎵/氮化鎵量子井基板上來探討量子點光色轉換效率的提升，放置於氮化矽中的沉積金屬奈米顆粒的侷域表面電漿子共振可以與量子井和量子點耦合，而合成金屬奈米顆粒的侷域表面電漿子共振可與混合之量子點耦合，耦合的效果可以使量子井以及量子點發光效率提升，增加量子井發光能進一步提升量子點發光效率，為了研究光色轉換效率我們製作不同的樣品結構來量測內部量子效率及光致發螢光衰減時間，經由侷域表面電漿子共振增強量子點在雷射激發波長以及量子井發光波長的吸收可以產生更有效的量子點發光或光色轉換，然而一個合成金屬奈米顆粒的侷域表面電漿子共振若是能涵蓋量子點吸收與放光波長，則可以更有效的增強光色轉換效率。

Five metal nanoparticles (NPs), including one kind of deposited metal NP (DMNP) and four kinds of synthesized metal NP (SMNP), are prepared for overlaying with quantum dots (QDs) on the top of either GaN or InGaN/GaN quantum well (QW) template to study the QD color conversion efficiency. The localized surface plasmon (LSP) resonance of the DMNP, which is embedded in a SiN layer, can couple with the QWs below and QDs above. The LSP resonances of the SMNP samples can couple with the mixed QDs. The coupling processes can enhance the emission efficiencies of QWs and QDs. The enhanced QW emission can further enhance QD emission. Different device structures are fabricated for investigating the color conversion efficiencies through the measurements of internal quantum efficiency and photoluminescence decay time. Generally speaking, enhancing QD absorption through LSP coupling at the QD pumping wavelengths, including pumping laser and QW emission wavelengths, can lead to more effective QD emission or color conversion. Nevertheless, an SMNP with its LSP resonance spectrum covering both QD absorption and emission wavelengths can even more effectively enhancing color conversion efficiency.