室溫下氮化銦鎵基底之核殼柱狀陣列的高階耦合迴廊模態光致激發雷射之研究

Abstract

近年來，透過形成微米或更小等級的共振腔形成的半導體雷射由於其極低的功率密度閥值引起世界各地廣大的研究興趣，常見的半導體雷射種類大致可以分成法布里-博羅雷射、光子晶體雷射、迴廊模態雷射等等，在這篇論文中，我們主要介紹的是迴廊模態的半導體雷射，然而常見的迴廊模態雷射面臨到的問題是隨著共振腔的變小導致漏光增加，以致其無法在做成極小元件時保有良好的功率，在工業的應用上受到限制。 因此，本論文中我們提出一種新穎的核殼柱狀奈米柱陣列的結構，在奈米柱的頂端有額外的氮化矽形成的鈍化層，預期透過使用這種結構生長而成的奈米柱可以形成以非極化面為主的量子井並且減少銦的自聚集現象，這些都有利於減少雷射共振腔的損耗，除此之外，本篇論文透過使用將奈米柱做成陣列的方式，希望可以將單一奈米柱共振腔的漏光耦合以達到相對低的功率密度閥值，這種陣列結構的另一個好處在於可以透過調變奈米柱之間的週期性以及氮化銦鎵量子井的銦含量等兩項參數使其模態共振波長與自發輻射波長重疊以達到可調變包含整個可見光波段的雷射。 在這篇論文中，我們成功的製備出一核殼狀奈米柱陣列的基板，並結合量測結果以及模擬進行討論，且與文獻上的各式迴廊模態雷射做比較以及討論，我們相信它將會是未來製備奈米尺度之迴廊模態雷射的重要方向。

In recent years, micro-scale or nano-scale semiconductor lasers have attracted intensive attention. Common type of semiconductor lasers include: Fabry-Perot lasers, photonic crystal lasers, and whispering gallery mode (WGM) lasers. In this thesis, we mainly introduced WGM laser. However, the additional losses accompanied with cavity size down to few hundred nanometers, deteriorated its performance with small cavities and limited its commercial application.

To overcome these challenges, we proposed a novel core-shell nanorods array laser structure. In our newly-design core-shell nanorod lasers, the top of nanorod was passivated by a Si3N4 layer. We expected that the quantum wells will be limited on non-polar planes and the In cluster could be suppressed by using this structure while both these phenomena reduce the scattering losses of cavity. Besides, in this thesis, we adopted the approach of fabricating nanorods in array to reduce losses by mode coupling among single nanorods and then achieved a relatively low threshold power density. Another advantage of this periodic structure is that the lasing peak is tunable in a wide-range by matching the resonant wavelength and the peak wavelength of spontaneous emission. The former could be achieved by tuning the cavity size and the periodicity of array, while the latter could be achieved by adjusting the In composition of multiple quantum well.

In this work, we successfully demonstrated our core-shell nanorods array laser, the measurement and simulation result will be explained, It is believed that our study will pave a way for the advancement of nano-scale WGM laser with excellent performance.