長共振腔之銦鎵鋁砷/磷化銦脊型波導分佈反饋雷射的光電與熱效應研究

Abstract

利用向聯亞光電工業股份有限公司所購買的事先已有製作週期性光柵的InP磊晶片來製作出在長度與寬度上不同組合搭配的分布式回饋雷射（Distributed Feedback, DFB）元件。實驗內容囊括一開始的光罩、製程設計、元件製程進行與問題解決，再到最後對各尺寸元件的電性和發光特性(光功率、光譜分布)進行量測。 光罩上將元件設計為共振腔尺寸長300/500/750/1250 μm，同時搭配寬度2/4/6 μm，一共12種不同元件尺寸。 製程上在製作脊型波導共振腔時，由於元件的最小寬度在2 μm，波導兩側的向下蝕刻採用乾蝕刻而非濕蝕刻，避免脊型波導的形狀因側向蝕刻或披覆層的包覆性不佳而被破壞。另外在透過電漿輔助化學氣相沈積(PECVD)沉積鈍化層氮化矽Si_3 N_4後，同樣受限於元件尺寸，在定義掩膜開洞時採用自我對準[1]的技術，避免可能遭遇的曝光機的繞射極限以及人為對準失誤。 最後就成品的元件表現(功率、頻譜模態、熱......等)去探討在過程中可能出現的失誤。

This study utilizes InP epitaxial wafer, which is previously procured from LandMark Optoelectronics Corporation, to fabricate Distributed Feedback (DFB) laser devices with various combinations of lengths and widths. The experimental process includes the design of photomasks, process planning, device fabrication with troubleshooting, and the analysis of the electrical and optical characteristics (optical power and spectral distribution) of the devices. The DFB laser devices were designed with resonant cavity lengths of 300, 500, 750, 1250 μm, paired with widths of 2,4, and 6 μm, resulting in a total of 12 device sizes respectively. Due to the minimum width of the devices was set at 2 μm, a dry etching process was implemented for the shape of waveguide instead of wet etching to preserve the shape of the ridge waveguide and avoid damage from lateral etching or poor conformality of the deposited film layer. Furthermore, after depositing a passivation layer of silicon nitride (Si_3 N_4) via Plasma-Enhanced Chemical Vapor Deposition (PECVD), self-aligned[1] techniques were adopted for the mask opening. This approach mitigated potential issues related to the diffraction limit of the mask aligner and manual alignment errors by human since the minimum width of the devices mentioned above.