熱蝕刻分子束磊晶0.78微米AlGaAs/GaAs雷射及高功率雷射端面鍍膜

Abstract

在這篇論文裡，我們介紹波長0.78微米，以砷化鎵/砷化鋁鎵為材料之半 導體雷射的製造，所採用的結構是自動對準異質接面式，使用分子束磊晶 系統的熱蝕刻及重複磊晶的方法來製作，這樣的結構在以分子束磊晶系統 長晶時就已經賦以元件內部限制電流的功能，因此具有高產量、高良率、 較低遠場繞射角比及易於控制模態分佈之優點。另外提及的工作包括元件 特性的量測及最佳化，目前的成果，以共振腔長250微米、寬4微米的元件 而言，在20C時，臨界電流為54mA、特性溫度為85.8K、遠場繞射角比為 1:2。在這篇論文裡，另外介紹高功率雷射端面鍍膜上的研究，藉由在半 導體雷射的端面鍍上一層或多層介電質薄膜以改變反射率、我們可以改善 半導體雷射的特性，增加功率的輸出，採用單層四分之一波長厚的二氧化 矽當抗反射膜可以將反射率由原來的30%改變為5%，而使用三對四分之一 波長厚的二氧化矽及二氧化鈦當高反射膜可將反射率提高至超過90%。 In this thesis, we present the fabrication of 0.78 micron self- aligned heteostructure semiconductor lasers. MBE thermal etching and regrowth are used to fabricate semiconductor lasers with cu- rrent blocking mechanism. Characteristics of the device including light-current relationship, spatial mode distribution, cavity length effect, cavity width effect and temperature effect are measured and discussed. Semiconductor lasers with a threshold cu- rrent of 54 mA at 20C, a characteristic temperature of 85.8K and a 1:2 ratio of farfield angles are fabricated using this process. We also present in this thesis the facet coating of high power lasers. Performance of the high power lasers is further improved by coatings of multilayer dielectric material to the facets. Anti-reflection coating which consists of single quarter- wavelength thick SiO2 film is deposited using E-gun to the front facet (the emission facet) to change its reflectivity from 30% as-cleaved facet) to 5%. While high reflection coating which consists of 3 pairs of quarter-wavelength thick SiO2 and TiO2 alternative layers are evaporated to the rear facet to increase the reflectivity to more than 90%.