Nitride Growth using Buffer Layers The Pretty Complete Story

1
Nitride Growth using Buffer Layers The Pretty
Complete Story

• Ted Wangensteen
• EEL 6935
• WBG I
• Spring 2003

2
Outline

• Introduction Why Nitrides?
• Literature Review
• Growth Background Problems encountered
• Improvements, in-situ Methods - Results
• Summary

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Why Nitrides?

• High Temp/Chem/Radiation Resistant Material
• Blue and UV LEDs , Blue completes the Color
  Spectrum
• High output, Lower Cost Lighting, i.e.
  Stoplights, Dashboards
• UV Photodectors
• Short Wavelength Laser gt Increase Optical
  Memory Storage

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Cutting Wavelength in Half - Quadrupules Data
Storage Capability
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References

• Nakamura, Shuji, Blue Laser Diode, The Complete
  Story , (2000), Springer.
• Ponce, Fernando, Crystal Defects and Device
  Performance in LEDs and LDs, Introduction to
  Nitride Semiconductor Blue Lasers and Light
  Emitting Diodes, Chapter 4, Nakamura, Ed., Taylor
  and Francis, (2000).
• DenBaars, S, Basic Physics and Materials
  Technology of GaN LEDs and LDs, Chap. 1, Ibid.
• Akasaki, I., Progress and Prospects of Group
  III Nitride Semiconductors, Blue Laser and Light
  Emitting Diodes III, (1998), Ohmsha, Japan.
• Wangensteen, T. , Pankove, J. ., GaN Growth,
  Astralux, Inc., Boulder, CO., (1999).

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Nitride Growth Issues

• Cleaning, Preparation want Clean, Flat Surfaces
• Doping difficult due to Int. Carrier
  Concentration
• Ohmic Contacts
• Large Scale Substrates Unavailable- nec. For
  Manu.
• Biggest Problem is Lattice/Thermal Mismatch of
  Substrates Example-GaN/Sapphire-Blue Diode

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Ponce, Fernando, Crystal Defects and Device
Performance in LEDs and LDs, Introduction to
Nitride Semiconductor Blue Lasers and Light
Emitting Diodes, Chapter 4, Nakamura, Ed., Taylor
and Francis, 2000.
8
Ponce, Fernando, Crystal Defects and Device
Performance in LEDs and LDs, Introduction to
Nitride Semiconductor Blue Lasers and Light
Emitting Diodes, Chapter 4, Nakamura, Ed., Taylor
and Francis, 2000.
9

• Ponce, Fernando, Crystal Defects and Device
  Performance in LEDs and LDs, Introduction to
  Nitride Semiconductor Blue Lasers and Light
  Emitting Diodes, Chapter 4, Nakamura, Ed.,Taylor
  and Francis, 2000.

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Example of Nitride Growth effect on development
of the Blue DiodeHistorical milestones (very
condensed version)

• -Proof of Concept, Potential for development
• Luminescence - Pankove, Maruska ( 1970 )
• 1st Blue LED Metal-Insulator-Semiconductor
  Pankove (1971)
• gt? Key Problem was Growth GaN grows laterally -
  had to wait until improved
• -Process Improvements - Breakthroughs
• Buffer Layer - Yoshida (1983)
• AlN Buffer Layers Akasaki (1986)
• P-Type GaN by Low Energy Electron Irradiation -
  Akasaki (1988)
• gtgt Namamura says Aha!
• - Device Manufacturing
• GaN Buffer Layer Nakamura (1991)
• High Output GaN LED Nakamura (1991)

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Akasaki, I., Progress and Prospects of Group
III Nitride Semiconductors, Blue Laser and Light
Emitting Diodes III, 1998, Ohmsha, Japan
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• Nakamura, Shuji, Blue Laser Diode, The Complete
  Story , 2000, Springer.

13
Nakamura, Shuji, Blue Laser Diode, The Complete
Story , 2000, Springer.
14
Akasaki, I., Progress and Prospects of Group
III Nitride Semiconductors, Blue Laser and Light
Emitting Diodes III, 1998, Ohmsha, Japan
15
Nakamura, Shuji, Blue Laser Diode, The Complete
Story , 2000, Springer.
16
Nakamura, Shuji, Blue Laser Diode, The Complete
Story , 2000, Springer.
17
Nakamura, Shuji, Blue Laser Diode, The Complete
Story , 2000, Springer.
18
Akasaki, I., Progress and Prospects of Group
III Nitride Semiconductors, Blue Laser and Light
Emitting Diodes III, 1998, Ohmsha, Japan
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Summary

• Nitrides have variety of practical uses
• Lattice-Therm mismatch problem
• Shown Stunning Material Improvements by using a
  Buffer Layer