新穎氮化鎵一維光子晶體發光元件研究

Abstract

在這篇論文中，我們成功製作出氮化鎵光子晶體奈米樑共振腔，其中包含布拉格反射類型與掏空類型，並研究其特性。在氮化鎵光子晶體奈米樑共振腔的研究中，不同於以往調變週期和孔洞大小來侷限光場和提高品質因子，我們利用能帶邊緣效應，將群速度為零的地方設計在我們所需的波長，使光場在奈米梁形成駐波共振；由於氮化鎵波長較短，對應元件尺寸縮小許多，為了降低製程難度，首先我們在光子晶體奈米梁共振腔的下方，利用磊晶布拉格反射鏡取代掏空結構，讓光場集中在上方主動層所在區域，並將製程量測結果和模擬搭配討論。除此之外，為了提高氮化鎵光子晶體奈米樑共振腔的品質因子，我們進一步嘗試用聚焦離子束系統來達成共振腔下方的掏空結構，使得光子晶體奈米樑共振腔的周圍皆為空氣所包覆，藉由此設計來增加折射率的差異，得到更好的光場侷限效果，並且進一步分析其光學特性。

In this thesis, we have demonstrated GaN-based one-dimensional photonic crystal nanobeam cavities for both on-DBRs type and membrane type. Their optical characteristics were also measured and analyzed. For the GaN-based one-dimensional photonic crystal on-DBRs nanobeam cavities , different from tuning the period and hole radius to enhance the optical confinement factor and quality factor, the band-edge mode GaN-based PC nanobeam cavities were designed and fabricated. In order to reduce the difficulty in fabrication, the epitaxy distributed Bragg reflector (DBR) was applied in GaN-based one-dimensional photonic crystal nanobeam resonators as the low index layer used to reflect light from bottom to increase the optical confinement in active region. For the subject of GaN-based photonic crystal membrane-type nanobeam cavities, we further fabricated the undercut structure by focus ion beam system. By this fabrication step, the refractive index difference between the cavity and the surrounding region would be larger and the optical confinement would be better. The optical characteristics were investigated by micro-photoluminesence measurement and identified the different resonant modes by simulations.