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高折射率對比表面光柵雷射和氮化鎵光子晶體奈米梁共振腔，並研究其特性。在氮化鎵高折射率對比表面光柵雷射的研究中，不同以往四周圍包附空氣作為低折射率層，我們利用磊晶布拉格反射鏡取代掏空結構作為底部低折射率層，並在模擬反射頻譜中看到譜線不對稱的現象，在物理學稱為費諾共振；費諾共振使原始自發性放射頻譜半高寬變窄，提高共振腔品質因子；我們成功利用此現象製作出室溫低閾域值雷射，並和模擬搭配探討其雷射特性。而在氮化鎵光子晶體奈米梁共振腔的研究中，不同於以往調變周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，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。

In this thesis, we have demonstrated GaN-based high contrast surface grating lasers and photonic crystal nanobeam resonators. Their optical characteristics were also measured and analyzed. For the subject of GaN-based high contrast surface grating (HCSG) lasers , different from the membrane type strucutre, the epitaxy distributed Bragg reflector (DBR) was used in GaN-based HCSG lasers as the low index layer and the reflectivity spectrum of it was observed the asymmeteric line shape which is called Fano resonance in the simulation results. This phenomenon would cause that the full width at half maximum (FWHM) in spontaneous emission spectrum becomes narrower and improves the cavity quality factor. Based on the Fano resonance, the low-threshold GaN-based HCSG lasers was realized at room temperature and confirmed the results with simulation. For the subject of GaN-based photonic crystal (PC) nanobeam resonators, 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 rasonators were designed and fabricated. In order to reduce the difficulty in fabrication, the epitaxy DBRs were used to reflect light from bottom without undercut structure to increase the optical confinement in active region. The optical characteristics were investigated by micro-photoluminesence measurement and identified the different resonant modes by simulations.