使用有機金屬氣相磊晶法成長砷化鋁鎵及無鋁組成之垂直共振腔面射型雷射及單模面射型雷射之研製

Abstract

本論文成功的使用有機金屬氣相磊晶法成長面射型雷射元件。首先，本文探討基本的面射型雷射設計的原則，主要著重於如何設計出具有高反射率及低阻值之布拉格反射器。 在實驗方面，由於主動層之品質對元件的特性非常重要，所以我們對主動層之砷化銦鎵量子井之成長做一番探討，並找出最佳的成長條件。在砷化鋁鎵面射型雷射方面，我們成功的長出高品質波長為980 nm的磊晶片，並研發出能快速鑑定晶片品質的方法，另外，也成功發展出低漏電流製程，進而製作出低臨界電流、可於室溫連續操作之元件。 在無鋁組成材料系統方面，也就是指磷化鎵銦與砷化鎵材料，在這兩個材料之間的介面及形成原因，一直有不同的爭議。我們成功的利用一晶格匹配的磷砷化鎵薄層及適當的氣體切換，長出世界最窄半高寬的無鋁組成材料量子井，並成功建立模型解釋此一介面形成之原因。亦利用此一技術，成功研發出無鋁組成材料之面射型雷射，但在研發的同時，我們發現利用夾一個薄層於兩無鋁組成材料之間的技術，對元件電性有很大的影響。另外，由於有機金屬氣相磊晶機台的硬體設計，與無鋁組成材料系統的介面有直接的關係，因此如果從硬體本身修改去減少銦原子的記憶效應，相信可同時改善此無鋁組成材料系統之光性與電性。 最後在850 nm單模面射型雷射方面，全世界均在努力研發，現在主要有用氧化製程及表面蝕刻兩種方式。我們利用鍺金屬做抗反射模的方式，成功做出單模操作之面射型雷射，單模操作之功率可到達一毫瓦特，近場之光性非常穩定，非常適宜做為下一代的通訊元件。

In this dissertation, we have successfully fabricated AlGaAs and Al-free Vertical Cavity Surface Emitting Lasers (VCSELs) by MOVPE system. Firstly, we discuss the design rule for the VCSEL, the main effort is put on how to achieve high reflectivity and low resistance distributed Bragg reflectors. (DBRs) Secondary, we have do many experiment to achieve the good quality of the active region of the VCSELs, and find the best condition to growth InGaAs quantum wells. We also succeed in epi high quality AlGaAs VCSEL epi wafer, and investigate the quick process of VCSEL to qualify the quality of epi wafer. By the way, we also developed the low leakage current process of VCSELs, and make a low threshold CW operation VCSEL devices. On the Al-free topics, that is to say GaAs and GaInP materials. The reason why the intermediate layer existed between the GaAs and GaInP is still under debate. We successfully made the world’s most narrow FWHM of PL spectrum (6.7 meV) by adding 1 nm lattice matched GaAsP between GaAs and GaInP to. We also built a In memory effect model to account the result. In the mean time, we have achieve the Al-free VCSEL by MOVPE. But we found, add 1nm GaAsP will drastically increased the resistance of the VCSEL devices. Because the In memory effect strongly related with the hardware of MOVPE system, especially the gas switches system. So we think to improve the hardware of MOVPE system maybe the direct way to improve the optical and electrical quality of Al-free materials Finally, we put some effort on single transverse mode VCSEL on 850 nm products. There are two methods to investigate the single mode VCSELs. One is use the small oxidation aperture, the other is use the surface relief technique. We use the Germanium as the anti-reflection coating material to spatially control the threshold of VCSELs. And we have made single transverse mode VCSEL and exhibit stable single lobe in near field measurement. So it is very suitable for the next generation’s communication devices.