Determination of exciton transition energy and bowing parameter of AlGaN alloys in AlGaN/GaN heterostructure by means of reflectance measurement

H. Jiang, G. Y. Zhao, Hiroyasu Ishikawa, T. Egawa, T. Jimbo, M. Umeno

Research output: Contribution to journalArticle

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Abstract

The normal-incidence reflectance measurement was employed to obtain the free exciton transition energy (EFX) of AlGaN alloys in AlxGa1-xN/GaN/sapphire heterostructure grown by metalorganic chemical vapor deposition. It was found that the thickness variation of the AlGaN layer may cause a noticeable change in the line shape of reflectance spectrum and impede the identification of the desired excitonic position. By using a reflection model of two absorbing layers with a transparent substrate, the experimental reflectance spectra were theoretically simulated and utilized to explain the reflection mechanism in AlxGa1-xN/GaN heterostructures. On the basis of the above analysis, the feasibility of the reflectance measurement for such heterostructures is confirmed. At room temperature, the EFXs obtained from the fitting showed an excellent agreement with the corresponding peak energies in the photoluminescence spectra. Furthermore, at the optical energy position about 100 meV above the EFX, the spectral feature of exciton-LO phonon interaction was observed in the reflectance spectrum record for low Al composition (x≤0.16). Using the Al mole fraction derived from x-ray diffraction measurement, the bowing parameter of the epitaxial AlGaN layer was determined. In the range of 0≤x<0.3, the resulting bowing parameter shows a downward value of 0.53 eV.

Original languageEnglish
Pages (from-to)1046-1052
Number of pages7
JournalJournal of Applied Physics
Volume89
Issue number2
DOIs
Publication statusPublished - 2001 Jan 15
Externally publishedYes

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excitons
reflectance
energy
metalorganic chemical vapor deposition
line shape
sapphire
x ray diffraction
incidence
photoluminescence
causes
room temperature
interactions

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physics and Astronomy (miscellaneous)

Cite this

Determination of exciton transition energy and bowing parameter of AlGaN alloys in AlGaN/GaN heterostructure by means of reflectance measurement. / Jiang, H.; Zhao, G. Y.; Ishikawa, Hiroyasu; Egawa, T.; Jimbo, T.; Umeno, M.

In: Journal of Applied Physics, Vol. 89, No. 2, 15.01.2001, p. 1046-1052.

Research output: Contribution to journalArticle

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AU - Egawa, T.

AU - Jimbo, T.

AU - Umeno, M.

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