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Structural and Optical Properties of InGaN/GaN Multi-Quantum Well Structures with Different Indium Compositions

Published online by Cambridge University Press:  01 February 2011

Chang-Soo Kim
Affiliation:
National Research Lab., Materials Evaluation Center, Korea Research Institute of Standards and Science(KRISS), Taejon, Korea 305-600
Sam-Kyu Noh
Affiliation:
National Research Lab., Materials Evaluation Center, Korea Research Institute of Standards and Science(KRISS), Taejon, Korea 305-600
Kyuhan Lee
Affiliation:
Optronix Inc., Taejon, Korea 305-380
Sunwoon Kim
Affiliation:
Photonic Device Group, Samsung Electro-Mechanics, Suwon, Korea 442-743
Jay P. Song
Affiliation:
SongJee Industrial Corporation, Sungnam, Korea 463-500
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Abstract

The structural and optical properties of InGaN/GaN multiple quantum wells (MQWs) grown on sapphire by MOCVD have been investigated using high-resolution XRD, PL and TEM. The samples consisted of 10 periods of InGaN wells with 6.5nm thickness. The designed indium compositions were 15, 20, 25 and 30% (samples C15, C20, C25, C30, respectively). The thickness of GaN barrier was 7.5nm. The MQW in sample C15 maintained lattice coherency with the GaN epilayer underneath, the MQWs in the other samples, however, experienced lattice relaxation. The crystallinity of the samples decreased considerably with In concentration. As In composition increased, PL peak energy showed a red-shift, and the FWHM of the peaks increased. The increase in the FWHM is attributed to the defects due to the lattice relaxation. For C25 the PL peak intensity increased sharply in spite of the defects due to the lattice relaxation of the sample. It is concluded that the results are related to the In-rich region due to indium phase separation which was observed by TEM image.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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