| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2018) | |
| Thin Films | Wednesday Sessions |
| Session TF-WeM |
| Session: | Nanostructural and Surface Morphological Evolution: Experiment and Theory |
| Presenter: | Yusuke Nakajima, Kogakuin University, Japan |
| Authors: | Y. Nakajima, Kogakuin University, Japan T. Honda, Kogakuin University, Japan T. Yamaguchi, Kogakuin University, Japan T. Onuma, Kogakuin University, Japan |
| Correspondent: | Click to Email |
Full-color micro-LED displays [1] requires a monolithic integration of blue, green and red LEDs. In this case, realization of GaInN-based red LEDs with high efficiencies is one of the technical issues. One of the difficulties of these fabrications is due to lattice mismatch between GaN and GaInN layers as the indium composition is increased [2]. At present, the GaInN substrate is still in the research stage. Thus, fabrication of GaInN underlying layers is one of the technique to overcome the lattice-mismatch problems. The lattice-relaxed underlying layers are required for the red LEDs. On the other hand, the lattice relaxation requires the generations of threading dislocations (TDs). These points show the GaInN underlying layers require the lattice relaxation and reduction of TDs. We consider that growth temperature is an important parameter in GaInN growth.
In this paper, lattice relaxation in GaInN layer growth by RF-MBE with different growth temperature is reported. Their photoluminescence (PL) spectra are also discussed. The growth temperatures were fixed at 520, 540, 560, 580 and 600 ° C. The indium compositions were of grown layers 25±5%. The lattice relaxations of these layers were estimated using the patterns of reciprocal space mapping in X-ray diffraction (RSM).
GaInN layers on GaN templates were grown by RF-MBE. GaN templates were grown by MOVPE. The growth time was 60 minutes. The thickness of all grown layer was approximately 0.4μm. The RSMs show that the high relaxation was observed from the low-temperature grown layer nevertheless indium compositions were constant of 25%. On the other hand, PL peaks were shifted towards higher energy side as a function of growth temperature. These mean that the high indium segregation will be occurred in the layers grown at low temperature. Detailed relaxation ratio depended on growth temperature will be discussed.
Acknowledgment
The authors would like to thank Spring-8, Dr. Sasaki and Takahasi of QST and Profs. Nanishi and Araki of Ritsumeikan University for their help with the experiments.
[1] Jacob Day et al., Appl. Phys. Lett. 99, 031116 (2011).
[2] S.Shinji et al., Appl. Phys. Lett 6 111004(2013).