氮化鎵微米孔矩陣發光二極體

Abstract

本論文討論以自我對準方式製作出的氮化鎵微米孔矩陣發光二極體其電性特徵和發光特性，孔洞直徑分別有3、7、11和15微米等四種大小，而且傳統的發光二極體也被製作在同樣的試片上做為比較的基楚。在相同20毫安培電流操作下發現，元件的電壓值會隨著孔洞直徑的增加而隨著上升，且都略高於傳統的發光二極體；在有相同的主動層面積時，直徑為7微米的微米孔矩陣發光二極體有最佳化的輸出功率，比傳統發光二極體提升了36%。又從失去面積佔整體主動層面積比例(γ)來分析，發現當γ為6%時，製作微米孔矩陣於發光二極體上對增加輸出功率有最大的增益;而當γ大於28%時，微米孔矩陣發光二極體的輸出功率開始出現比傳統發光二極體弱的情況。從模擬和實驗二方面對氮化鎵微米孔矩陣發光二極體得到最佳化設計。 之後我們將微米孔矩陣應用於大面積的發光二極體上，並且比較用鎳/金和氧化銦錫二種不同的透明電極在大面積微米孔矩陣發光二極體上的影響。結果發現用氧化銦錫當做透明電極的大面積微米孔矩陣發光二極體和用鎳/金當透明電極的大面積微米孔矩陣發光二極體比較，在相同的孔洞大小時元件的阻值都比較小，且發生輸出光功率出現衰退的電流值都比較高。量測它們的遠場分佈發現，製作微米孔矩陣並不會影響發光二極體的發散角，且發散角的角度分佈在75°到80°之間。

GaN-based micro-hole array LEDs, with hole diameter= 3、7、11 and 15 μm, were fabricated with self-aligned technique. The electrical and light output properties of the micro-hole array LEDs are studied and compared that of the conventional broad-area (BA) LEDs. The forward bias voltage, VF, of the GaN-based micro-hole array LEDs at a driving current of 20 mA increases with d and slightly exceeds that of the conventional BA LEDs. The light output from the micro-hole array LEDs was over 36% grater than that from conventional LEDs with the same device areas. Besides, the enhancement factor of light output from the experimental data decreases as γ increases above 6% (d > 7 µm) and no enhancement is observed from the micro-hole array LEDs at γ > 28%. The optimal design for the GaN-based micro-hole array LEDs are achieved in this work by the experiment and simulation methods. Furthermore, the optimal design of micro-hole array is used on the GaN-based large-area LEDs. Two kinds of electric conductive material of ITO and Ni/Au are used as the transparent contact layer to the GaN-based large-area micro-hole array LEDs. The results showed that the transparent contact layer of ITO not only decreased the device resistance but also extend the roll-over current. From the emission far-field pattern of LEDs, we found that the micro-hole array on LEDs have little influence on the far field angle. At FWHM, the far field angles are in the range of 75° ~ 80°.