Studies on Optical and Material Properties of InGaN Thin Films with Different Sidoping Conditions

1
Studies on Optical and Material Properties of
InGaN Thin Films with Different Si-doping
Conditions

• Advisor Dr. C. C. Yang
• Student Chih-Chung Teng
• Graduate Institute of Electronics Engineering
• National Taiwan University

2
Outline

• Introduction
• Applications
• Spinodal Decomposition, S-shaped Behavior,
  Compositional Pulling Effects, Si-doping Effects,
  Thermal Annealing Effects, etc.
• Research Motivations and Topics
• Characterization of As-grown Samples
• Sample Structures, PL, PLE, TRPL, CL, SEM and
  HRTEM Results.
• Thermal Annealing Effects
• PL, TRPL, CL, and AFM Results.
• In-depth Investigations of InGaN Thin Films
• PL, TRPL, CL, and SEM Results.
• Conclusions

3
Research Motivations and Research Topics

• Although many research have been reported about
  optical properties of Si-doped InGaN thin films,
  the optical and nano-material properties far
  beyond the critical thickness are rarely
  reported. In such a case, the effects dominating
  under the critical thickness, i.e., the strain
  effect induced by lattice mismatch near the
  interface, can be neglected.
• Part 1 Optical and material characteristics of
  the undoped and Si-doped InGaN samples.
• Part 2 Thermal annealing effects.
• Part 3 In-depth investigations of the thin films
  with various etching depths.

4
Conclusions

• We have investigated the optical properties and
  material nano-structures of undoped and Si-doped
  InGaN thin films.
• With Si-doping in InGaN thin film, we have found
  that a stronger localized state emission, which
  led to the S-shaped behavior, in PL spectrum and
  thus enhanced the integrated intensity.
• The localized state emission in Si-doped sample
  could be enhanced by thermal annealing due to the
  In-rich clusters change in structure and
  distribution.
• In-depth measurement results showed that a
  stronger clustering structure existed in deeper
  layers. The different trend of CL spectral peak
  position shift can be attributed to the better
  strain relaxation in deeper layers of the
  Si-doped sample.