我們使用磷砷化銦鎵/磷化銦材料製作具有光點轉換效果之埋入式雷射。在水平光點轉換方面，利用微影蝕刻製作漸變型脊狀波導，而在垂直光點轉換方面，採用Guard waveguide(GW)：加入一對階梯狀被動波導於主動波導層兩側，以擴大光場分佈。主動波導層則採用Separate Confinement Heterostructure (SCH) ：在多層量子井的兩側加入階梯式折射率波導結構，以增加主動層的電荷侷限。最後利用再磊晶的方法，將脊狀波導埋入p型及n型半導體中，使得脊狀波導的周圍形成p-n-p的介面，利用這樣的介面使注入載子完全進入主動層，以達到限電流的效果。將我們所設計的結構加以模擬計算後，得到遠場發散角為21ox21o (水平x垂直) 。
研究的成果，階梯狀被動波導的結構設計，內部效率(Internal efficiency)為63%。而在製作埋入式雷射方面，則由於二次磊晶時p型及n型半導體摻雜的濃度太高，造成漏電流太大，使得雷射無法發光。

We present the fabrication of InGaAsP/InP buried heterostructure spot-size converter lasers. In the lateral conversion, we use photolithography to make tapered ridge waveguides. In the vertical conversion, we use a pair of step-index passive waveguides, namely guard waveguides (GWs), in the two sides of the step-index active waveguide region to increase optical-field profile. In order to decrease leakage current, we use a p-n-p current blocking structure by MOCVD regrowth. From numerical simulations, the far-field divergence is 21x21.

The step-index GW structure shows an internal efficiency of 63%. However, the BH lasers did not lase from our fabrication processes. From the I-V characteristics, a large leakage current has bypassed through the blocking structure. The reason may relate to the high background doping concentration of our MOCVD growth.

第一章 緒論
第二章 半導體雷射之基本原理
第三章 結構設計
第四章 製程步驟
第五章 結果與分析
第六章 結論
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