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Applied Science and Convergence Technology 2007; 16(1): 27-32

Published online January 1, 2007

Copyright © The Korean Vacuum Society.

Phenomenological Study on Crystal Phase Separation in InGaN/GaN Multiple Quantum Well Structures

S. J. Lee,J. O. Kim,C. S. Kim,S. K. Noh,K. Y. Lim

Abstract

We have investigated photoluminescence(PL) spectra of four InxGa1-xN(x=0.15)/GaN multiple quantum well(MQW) structures with different well widths in order to study a phenomenon on crystal phase separation. The asymmetic behavior of PL spectra becomes stronger with increase of the well width from 1.5 ㎚ to 6.0 ㎚, which indicates dual-peak nature. Analyzing the dual-peak fit PL spectra, we have observed that the intensity of low-energy shoulder peak rapidly becomes stronger, compared to that of high-energy peak corresponding to a transition in InGaN QW. It suggests that InGaN QW has two phases with tiny different In compositions, and that In-rich(InN-like) phase forms more and more relatively than stoichiometric InGaN(x=0.15) phase by the InN phase separation mechanism as the QW width increases. PL spectrum of 6.0-㎚ sample shows an additional peak at low-energy region(~ 2.0 eV) whose energy position is almost the same as a defect band of yellow luminescence frequently observed in GaN epilayers. It may be due to a defect resulted from In deficiency formed with development of the phase separation.

Keywords: InGaN/GaN,다중양자우물,발광 스펙트럼,상분리,황색 발광준위,Multiple quantum well(MQW),Photoluminescence,Phase separation,Yellow luminescence band

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