Comparison of optical properties of GaN/AlGaN and InGaN/AlGaN single quantum wells

Shigefusa F. Chichibu, Amane Shikanai, Takahiro Deguchi, Akiko Setoguchi, Rikuro Nakai, Hisayuki Nakanishi, Kazumi Wada, Steven P. DenBaars, Takayuki Sota, Shuji Nakamura

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Abstract

Static, field-modulated and time-resolved spectroscopies were carried out to compare the electronic states between GaN/AlGaN binary and InGaN/AlGaN ternary single quantum wells (SQWs). The internal field that exists across the quantum well (QW) naturally induces a quantum-confined Stark effect (QCSE), namely the redshift of the QW resonance energy and decrease of the electron-hole wavefunction overlap. The GaN/AlGaN SQW exhibited a weak emission due to QCSE. However, optical absorption and degenerate pump-probe measurements revealed that excitonic character was maintained for thin QWs with the well width nearly the same as the bulk free exciton Bohr radius even under an electric field as high as 0.73 MV/cm. A slightly In-alloyed InGaN SQW exhibited a bright luminescence peak in spite of an effective bandgap inhomogeneity in the QW, which was confirmed by the point excitation and monochromatic cathodoluminescence (CL) mapping method. The lateral interval of each light-emitting area was estimated from the spatial resolution of the CL mapping to be smaller than 60 nm. Such local potential minima is considered to be formed due to the presence of a structure similar to quantum-disks [M. Sugawara: Phys. Rev. B 51 (1995) 10743]. Carriers generated in the InGaN QWs are effectively localized in these regions to form localized QW excitons exhibiting highly efficient spontaneous emissions.

Original languageEnglish
Pages (from-to)2417-2424
Number of pages8
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume39
Issue number4 B
Publication statusPublished - 2000 Dec 1

Keywords

  • Effective bandgap inhomogeneity
  • InGaN
  • Localization
  • Localized quantum well excitons
  • Piezoelectric field
  • Quantum-confined Stark effect

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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    Chichibu, S. F., Shikanai, A., Deguchi, T., Setoguchi, A., Nakai, R., Nakanishi, H., Wada, K., DenBaars, S. P., Sota, T., & Nakamura, S. (2000). Comparison of optical properties of GaN/AlGaN and InGaN/AlGaN single quantum wells. Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, 39(4 B), 2417-2424.