利用電子束微影技術於氮化鎵表面製作次波長週期結構增加發光二極體光萃取率

Abstract

本篇論文係採用電子束微影搭配電感耦合式電漿蝕刻於氮化鎵系列發光二極體的表面P型氮化鎵上製作次波長光柵週期性結構，用以提升發光二極體的亮度。藉由高解析的聚焦離子束顯微鏡來確認製作完成的表面結構，並利用微觀光致激發螢光光譜量測由主動層發出藍光訊號強度。 本論文研究主題可區分為兩大部分。第一部分，製作一維次波長光柵週期性結構於發光二極體表面，並且使用改變雷射功率大小，校正雷射到達主動層之量，增加實驗之準確度。第二部分，製作二維次波長光柵週期性結構於發光二極體表面，其中包含了孔洞結構與柱狀結構。針對孔洞與柱狀結構之相對PL峰值強度，探討其差異性並且說明其物理意義。

In this dissertation, for improving the light extraction efficiency, electron-beam lithography and inductively plasma dry etching were used to achieve sub-wavelength grating-periodic structures with exact dimensions on the p-side of nitride-based LEDs with multiple quantum wells. The surface morphology of accomplished sub-wavelength grating-periodic structures was re-examined with the instrument of FEI Dual-Beam NOVA 600i Focused Ion Beam, and the related blue light emitting from active region was measured by micro-photoluminescence (μ-PL) system. The main focus of the dissertation can be divided into two parts. First, the one-dimensional (1D) sub-wavelength grating-periodic structures were demonstrated. In order to accomplish the accuracy of the measured data, a method of excitation power dependent μ-PL measurement was introduced subsequently. Second, we showed the two-dimensional (2D) sub-wavelength grating-periodic structures, including hole and pillar structures. According to the differences between the relative PL peak intensity of hole and pillar structures, we can explore the physical mechanism of light extraction of nitride-based LEDs.