氧化鋅奈米線電漿子雷射

Abstract

近年來光電元件正朝著小尺寸以及低功耗的方向發展以期達成高密度光積體元件的實現，雖然半導體元件製程技術已經成熟發展出奈米尺度的元件，光波的波長使得發光元件受限於繞射極限而無法朝向奈米尺度發展。本研究團隊以氧化鋅奈米線為增益介質並放置在隔著一層介電質薄膜的金屬上(SIM結構Semiconductor-Insulator-Metal structure)，藉此形成法布里-裴洛表面電漿子(Fabry-Perot type surface plasmon or surface plasmon polariton)共振腔的表面電漿子雷射。表面電漿子共振腔與傳統光學共振腔一樣具高度同調性的特性，且具高度同調性的表面電漿子可以由奈米線所形成的法布里-裴洛共振腔端點以光子的形式放出，由於放出的光子與共振腔內的表面電漿子具有一對一的對應特徵，從共振腔放出的光子亦具有高度的同調性。利用激子-表面電漿子(exciton-surface-plasmon)之間的耦合作用本團隊實現了可室溫操作的紫外光奈米電漿子雷射。這種紫外光奈米電漿子雷射在許多應用方面例如生物感測、光儲存、次波長成像、積體光路光源以及光學蝕刻等均極具潛力! 本論文主要探討表面電漿雷射在銀以及鋁基板下的雷射特性。首先，在以鋁為基板的表面電漿子雷射研究當中，我們證實了金屬薄膜品質與表面形貌的粗糙程度將會對電漿模態造成散射使得閾值大幅上升，經過適當製程方法可以增進表面電漿子雷射的表現，並成功達成室溫雷射操作。接著，我們藉由高品質的銀基板來降低表面電漿子雷射的金屬損耗，成功觀察到操作在表面電漿頻率下的雷射現象，透過鋁基板的奈米雷射與銀基板的奈米雷射的特性比較，我們歸納出表面電漿子雷射操作在接近以及遠離表面電漿頻率時的特性。最後，我們藉由理論的預測，在選擇適當的介電層以及金屬介電係數組合的條件下，表面電漿子雷射的SIM結構可以再進行簡化，透過製成的優化，我們成功的實現在高品質鋁基板上達成353 K高溫操作的表面漿子雷射。

The use of small optoelectronic devices with low power consumption for the realization of high-density integrated optoelectronic integrated circuits has attracted increasing interest in recent years. Although current semiconductor device manufacturing technology enables the development of nanoscale semiconductor optoelectronics, these devices are still restricted by the optical diffraction limit and cannot be further shrunk to nanoscale. In our research, we realized a Fabry–Perot-type surface plasmon polariton (SPP) laser by placing an insulator between a ZnO nanowire and metal film, forming a semiconductor–insulator–metal (SIM) structure. Because the emitted photons have characteristics in one-to-one correspondence with those of cavity surface plasmons (SPs), these photons also show coherent signatures. Our group has successfully demonstrated a SPP nanolaser that can be operated at room temperature through coupling between ZnO excitons and SPPs. Nanolasers with an ultracompact footprint can provide high-intensity coherent light, which can be potentially applied to high-capacity signal processing, biosensing, and subwavelength imaging. In this dissertation, we focus on the characteristics of a ZnO nanowire laser with silver- and aluminum-based thin film. In the first part, we demonstrate that the quality of the metal thin film and surface morphology increased the threshold significantly in an aluminum-based SPP nanolaser. By improving metal quality and surface roughness, we successfully enhanced the performance of the SPP nanolaser and achieved laser operation at room temperature. In the second part of this dissertation, we successfully demonstrate SPP nanolaser operation nearby the SP frequency by using a high-quality silver film with low metal loss. The characteristics of SPP nanolasers operating nearby the SP frequency are investigated in the silver-based SPP nanolaser. We then summarize the characteristics of the SPP nanolaser when it is operated at different distances from the SP frequency. In the final part of this dissertation, we show that by selecting the appropriate combination of permittivity between the metal and dielectric layers, the insulator layer of the SIM structure can be removed. The optimization of the SPP nanolaser structure can be sustained at temperatures of up to 353 K.