運用不同排列之二維光子晶體來探討空氣佔有率與氮化銦鎵類發光二極體光萃取增益之關係

Abstract

本篇論文運用不同排列之二維光子晶體來探討空氣佔有率與氮化銦鎵類發光二極體光萃取增益之關係。該等二維週期性奈米光子晶體係採用電子束微影方式搭配乾式蝕刻形成。 運用表面週期性光子晶體來提升氮化銦鎵類發光二極體之亮度已經廣泛地被探討，肇因於其可大幅地提升氮化銦鎵類發光二極體之光萃取增益。然而，於設計光子晶體時須仔細地考慮三項要素，分別為週期、深度以及空氣佔有率。但截至目前為止，於文獻上鮮少對於光子晶體之空氣佔有率與氮化銦鎵類發光二極體光萃取增益進行深入探討。有鑑於此，不同排列以及形狀的二維光子晶體之空氣佔有率與氮化銦鎵類發光二極體光萃取增益之關係，將於本篇論文中進行深入探討。 本篇論文之內文包含二維光子晶體之設計製作與量測分析。於光學量測方面，光致激發螢光頻譜系統可用於決定相對發光強度；積分球量測系統可用於決定相對光譜輻射通量，並同時可驗證光致激發螢光頻譜量測數據之趨勢。除此之外，將表面具有二維光子晶體之發光二極體磊晶片經由業界之標準製程，制備高功率氮化銦鎵類發光二極體之晶粒。該高功率氮化銦鎵類發光二極體之晶粒將可用於測定發光二極體之相對發光強度以及遠場光型的量測。根據實驗之結果，首先，無論二維光子晶體之排列以及形狀為何，氮化銦鎵類發光二極體之光萃取增益均於空氣佔有於51%時達到最大值，且隨著空氣佔有率之變化均有一類似之趨勢；再者，當具有六角排列二維光子晶體之發光二極體晶粒操作於350微安培時，其光輸出功率相較於不具結構之晶粒可大幅提升達81.9%；又，六角排列之光萃取增益優於四角排列，且具有較明顯之側邊出光指向性，可符合顯示器之需求。

This doctoral dissertation utilizes two dimensional (2-D) photonic crystals (PhCs) in different arrangement to investigate the correlation between the air duty cycle (ADC) and the light extraction enhancement (LEE) of InGaN-Based light-emitting diodes (LEDs). The 2-D periodical nano PhCs were achieved by using e-beam lithography and the dry etching technique. Implementing 2-D PhCs to improve the light extraction efficiency of InGaN-based LEDs has been pursued widely, due to the significant improvement of the LEE while using PhCs. Thus, in implementing 2-D PhCs, there are three main parameters should be taken into consideration carefully. They are lattice constant, depth, and ADC. Until now, there have been few literature reports on investigating the correlation between the ADC and the LEE of the InGaN-based LEDs so far. As a result, the correlation between the ADC and the LEE of InGaN-Based LEDs is investigated in this dissertation. The design and fabrication of 2-D PhCs and characterizations works are performed in the study. In optical measurement, micro-photoluminescence (μ-PL) measurements were used to provide comparison of the relative PL intensity. Integrating sphere (IS) measurements were used to decide the relative spectral radiant flux and also verify the trend observed in the μ-PL measurements. In addition, the characterizations of the LED devices were performed for extracting the light output power (LOP) and the far field radiation patterns of the LEDs. The finding first shows that the correlation between the ADC and the LEE of the 2-D PhCs LEDs is independent of the geometry and the shape of the 2-D PhCs, the LEE all reaches maximum value with the ADC of 51 % and has similar ADC dependent characteristic; besides, the LOP of the 2-D PhCs LEDs in hexagonal lattice arrangement (HLA) with the ADC of 51% are significantly improved by 81.9% as compared to the reference LED at an injection current of 350 mA; moreover, the better side-directional emission property of the 2-D PhCs LEDs in HLA than that in square lattice arrangement (SLA) has also been reported, which satisfies the requirement of display.