Fabrication and Characterization of Edge-Emitting Semiconductor Lasers Junyeob Song Rose-Hulman Institute of Technology, [email protected]
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Rose-Hulman Institute of Technology Rose-Hulman Scholar Graduate Theses - Physics and Optical Engineering Graduate Theses Spring 5-2014 Fabrication and Characterization of Edge-Emitting Semiconductor Lasers Junyeob Song Rose-Hulman Institute of Technology, [email protected] Follow this and additional works at: http://scholar.rose-hulman.edu/optics_grad_theses Part of the Other Engineering Commons, and the Semiconductor and Optical Materials Commons Recommended Citation Song, Junyeob, "Fabrication and Characterization of Edge-Emitting Semiconductor Lasers" (2014). Graduate Theses - Physics and Optical Engineering. Paper 1. This Thesis is brought to you for free and open access by the Graduate Theses at Rose-Hulman Scholar. It has been accepted for inclusion in Graduate Theses - Physics and Optical Engineering by an authorized administrator of Rose-Hulman Scholar. For more information, please contact bernier@rose- hulman.edu. Fabrication and Characterization of Edge-Emitting Semiconductor Lasers A Thesis Submitted to the Faculty of Rose-Hulman Institute of Technology by Junyeob Song In Partial Fulfillment of the Requirements for the Degree of Master of Science in Optical Engineering May 2014 ROSE-HULMAN INSTITUTE OF TECHNOLOGY Final Examination Report Name Graduate Major Thesis Title ____________________________________________________ ______________________________________________________________ DATE OF EXAM: EXAMINATION COMMITTEE: Thesis Advisory Committee Department Thesis Advisor: PASSED ___________ FAILED ___________ ABSTRACT Song, Junyeob M.S.O.E Rose-Hulman Institute of Technology May 2014 Fabrication and Characterization of Edge-Emitting Semiconductor Lasers Dr. Paul O. Leisher The semiconductor laser was invented in 1962, and has recently become ubiquitous in modern life. This thesis focuses on the development of a semiconductor laser fabricating process which utilizes semiconductor manufacturing technology in a cleanroom environment including photolithography, etching, deposition, and bonding processes. A photomask for patterning is designed, recipes of photolithography process and etching process are developed with experiments. This work gives how to develop the process of fabrication and determine the parameters for each processes. A series of semiconductor laser devices are then fabricated using the developed process and characterization is performed to assess device performance with industrial standard methods. A fabricated device has 18W power and 11% conversion efficiency. ACKNOWLEDGEMENTS I am very grateful to all of those who have helped me see this work come to fruition. First and foremost, I would like to thank my adviser, Professor Paul Leisher, who provided direction, encouragement, and support throughout all of the past quarters. He has always been there for guidance and has always helped his students. It has been honor to have him as my advisor. I would like to thank Professor Younghak Cho, my formal advisor in Korea. He introduced me to this microfabricaion field. He has always shown new challenges and helped me. I would also like to thank Ting Hao, my research partner, for her help with characterization of the fabricated devices. She has always been helpful. I would like to thank the Graduate, Physics and Optical Engineering Departments at Rose-Hulman Institute of Technology, and Mechanicl System Design Engineering Department at Seoultech for their financial support during my graduate studies and the opportunities that they have given. I would also like to thank Benjamin Hall for helping to check the grammar in thesis, Sangbin Lee for helping to search references, and Brian Fair for helping to use the cleanroom. Last but not least, I would like to thank my family in Korea for their encouragement and support because without it, all of this would not have been possible. iii TABLE OF CONTENTS ABSTRACT ....................................................................................................................... iii ACKNOWLEDGEMENTS ............................................................................................... iv TABLE OF CONTENTS ................................................................................................... iii LIST OF FIGURES .............................................................................................................v LIST OF TABLES ...............................................................................................................x 1. Introduction ..................................................................................................................1 1.1 Motivation ............................................................................................................1 1.2 Semiconductor Laser Diodes ...............................................................................2 1.3 Semiconductor Fabrication Device Structure ......................................................7 1.4 Epitaxial layer ....................................................................................................10 1.5 Rate equations ....................................................................................................12 1.6 Scope of Work ...................................................................................................15 2. Process Development .................................................................................................16 2.1 Overview of Fabrication Process .......................................................................16 2.1.1 Epitaxial Growth ............................................................................................17 2.1.2 Mesa Lithography ..........................................................................................18 2.1.3 Mesa Etch.......................................................................................................20 2.1.4 Contact Window Definition ...........................................................................22 2.1.5 Metallization ..................................................................................................24 2.1.6 Cleave, Coat and Bond ..................................................................................26 2.2 Mask Design ......................................................................................................29 iv 2.3 Photolithography Process Development ............................................................36 2.4 Etch Process – Mesa & Oxide ...........................................................................45 2.4.1 Determine semiconductor and oxide etch rates .............................................45 2.5 Metal Deposition Process ..................................................................................50 2.6 Bonding Process.................................................................................................54 2.7 Final Process ......................................................................................................57 3. Laser Characterization ...............................................................................................59 3.1 Power, Voltage and Power conversion efficiency vs. Current ..........................61 3.2 Spectrum at several current value ......................................................................65 3.3 Near-field Measurement ....................................................................................69 3.4 Divergence (Far-field) Measurement .................................................................71 3.5 Analysis..............................................................................................................73 4. Conclusion .................................................................................................................75 APPENDIX A – Device C Epitaxial Structure design ......................................................83 APPENDIX B – AZ5214E IR Data Sheet .........................................................................84 v LIST OF FIGURES Figure 1 Schematic cross-sectional views of a semiconductor laser diode along the lateral direction ........................................................................................................3 Figure 2 Schematic cross-sectional views of a semiconductor laser diode along the longitudinal direction ...............................................................................................3 Figure 3 Illustration of energy diagram of (a) double hetero structure and (b) a quantum well structure .............................................................................................5 Figure 4 Schematic diagrams depicting the evolution of the conduction band structure in the transverse direction: (a) double heterostructure, (b) separate confinement heterostructure (SCH), (c) graded-index separate confinement hetero structure(GRIN-SCH), (d) single quantum well hetrostructure (QWH), and (e) multiple quantum well (MQW) ...............................................................................6 Figure 5 Schematic diagram of an oxide defined stripe geometry .................................7 Figure 6 Illustration of an edge-emitting diode structure ...............................................8 Figure 7 Schematic drawings of (a) the buried heterostructure (BH) laser and (b) the ridge waveguide laser ..............................................................................................9 Figure 8 Sample SEM picture buried heterostructure