"Study of Indium Tin Oxide (ITO) for Novel Optoelectronic Devices"
Ph.D. thesis by Shabbir A Bashar


Table of Contents


  1. Introduction

  2. Background Theory and Literature Review

  3. Device Fabrication and Processing

  4. Measurement and Analysis Techniques

  5. Indium Tin Oxide (ITO): Experiment and Results

  6. Application of Transparent ITO Contacts
    • 6.1. Devices Based on the Schottky Contact
      • 6.1.1. Results on Metal/n-GaAs Schottky Diodes
        • 6.1.1.1. Diode Fabrication
        • 6.1.1.2. I-V Results
        • 6.1.1.3. Analysis and Modeling
        • 6.1.1.4. Al/n-GaAs Schottky Diodes
        • 6.1.1.5. Conclusion
      • 6.1.2. Fabrication and Process Optimization for ITO/n-GaAs Schottky Diodes
        • 6.1.2.1. The Effect of Mesa Etch and Post Deposition Annealing
        • 6.1.2.2. Effect of r.f. Power and ITO Film Thickness
        • 6.1.2.3. Diodes Fabricated at 150W r.f. Power Followed by Gradual Annealing
          • 6.1.2.3.1. ITO/In/n-GaAs Schottky Photodiodes - Sample A
          • 6.1.2.3.2. ITO/n-GaAs Schottky Photodiodes - Sample B
        • 6.1.2.4. Discussions and Conclusion
      • 6.1.3. Richardson Constant for the ITO/n-GaAs Contact
        • 6.1.3.1. Results and Discussion
      • 6.1.4. Realisation of Transparent Gate HEMT using ITO
        • 6.1.4.1. Fabrication
        • 6.1.4.2. Results and Discussion

    • 6.2. Devices Based on ITO Ohmic Contacts
      • 6.2.1. ITO Ohmic Contacts to n+ and p+ Epitaxial Layers
        • 6.2.1.1. Contacts to Highly Doped GaAs Epitaxial Layers
          • 6.2.1.1.1. Fabrication and Post Deposition Annealing
          • 6.2.1.1.2. Results and Comparison with Conventional Contacts
        • 6.2.1.2. Contacts to Highly Doped InGaAs Epitaxial Layers
          • 6.2.1.2.1. Fabrication and Post Deposition Annealing
          • 6.2.1.2.2. Results and Comparison with Conventional Contacts
        • 6.2.1.3. Surface Morphology of ITO Ohmic Contacts
      • 6.2.2. Realisation of ITO Contacts to HPT Emitters
        • 6.2.2.1. Fabrication of Conventional HBTs and ITO Emitter Contact HPTs
        • 6.2.2.2. Electrical Properties of HBTs with Opaque and Transparent Contacts
          • 6.2.2.2.1. AlGaAs/GaAs Devices
          • 6.2.2.2.2. InGaP/GaAs Devices
          • 6.2.2.2.3. InP/InGaAs Devices
          • 6.2.2.2.4. Sputter Damage in HPT Devices
          • 6.2.2.2.5. Comparison Between AlGaAs/GaAs, InGaP/GaAs and InP/InGaAs HBTs
        • 6.2.2.3. Optical Properties of HBTs
          • 6.2.2.3.1. Output Characteristics
          • 6.2.2.3.2. Spectral Response and Absolute Responsivity
          • 6.2.2.3.3. Top versus Edge Coupling and Design Considerations

    • 6.3. Spectral Response of Photodetectors

  7. Conclusions

  8. Further Work

© 1998: Shabbir A. Bashar (in accordance with paragraph 8.2d, University of London Regulations for the Degrees of M.Phil. and Ph.D., October 1997). The Copyright of this thesis rests with the author, and no quotation from it or information derived from it may be published without the prior written consent of the author.
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