All - Epitaxial Mode - and Current - Confined GaAs - Based Vertical - Cavity Surface - Emitting Lasers

Acknowledgements I would like to express my deep appreciation to my supervisor, Dr. Dennis G. Deppe, for leading me into the exciting semiconductor laser field and for his inspiring and insightful guidance throughout this course of research. In addition, I would like to thank my excellent committee members, Dr. learned semiconductor processing and MBE crystal growth 101 from them, and also received a lot of valuable advice both in research and in my stay at UT. I can't forget the everyday discussion and collaboration with Hua Huang, Jaemin Ahn, Qingwei Mo and Chuanshun Cao. They made my PhD study more enjoyable. Many thanks go to Dr. Sabine Freisem, who relieved me from a lot of heavy MBE maintenance work. I also want to thank my fellow group members, Deepa, Sonia, Zhihong, Manhong, Sam and Mathilde for their assistance and companionship. To my beloved wife, Wei, you are the happiness in my life. I thank God for sending you to me. Special appreciation goes to my parents and my sister, who have been there supporting me and encouraging me all my life. Oxide-confined vertical-cavity surface-emitting laser (VCSEL) emerged as a very attractive light source due to its optical mode-confinement, simultaneous current-confinement, and the resulting low threshold. However, oxide-confinement has serious drawbacks due to the reliability issue and the strain problem among others. In this dissertation, a new all-epitaxial VCSEL with all-semiconductor structure and simultaneous mode-and current-confinement is introduced and aims at attacking the oxide-confined VCSEL limitations. The benefits of the new technology include high performance, reliability, uniformity and the capacity for intracavity patterning. VCSEL performance is mainly determined by how effectively photons and carriers are confined. A lithographically defined intracavity phase-shifting mesa is used for mode confinement. Mesa height and placement in the cavity are carefully considered to achieve excellent optical loss control including both the vi diffraction loss and the scattering loss. A specially designed VCSEL incorporating the intracavity phase-shifting mesa successfully demonstrates mode-confinement. Selective interfacial Fermi-level pinning is used for current-confinement. Regrowth on oxidized AlGaAs off the intracavity mesa results in Fermi-level pinning at the interface and a valance band barrier for holes, providing current blocking. Regrowth on oxidized AlGaAs is challenging. Factors considered for surface protection and controlling regrowth surface roughness are: (a) sacrificial layers, (b) the Al ratio in the AlGaAs to be regrown on, and (c) the regrowth temperature. An all-epitaxial mode-and current-confined GaAs-based VCSEL is …