Improved Emission Efficiency in InGaN / GaN Quantum Wells with Compositionally-Graded Barriers Studied by Time-Resolved Photoluminescence Spectroscopy

Takeyoshi Onuma, Yoshimasa Uchinuma, Eun Kyung Suh, Hyung Jae Lee, Takayuki Sota, Shigefusa F. Chichibu

    Research output: Contribution to journalArticle

    9 Citations (Scopus)

    Abstract

    Recombination dynamics in InGaN/GaN multiple quantum wells (MQWs) having different well/barrier potential profiles were studied. Time-resolved photoluminescence (TRPL) signals of the MQWs having regular potential profiles (rectangular MQW) and those having the compositionally-graded barriers (trapezoidal MQW) exhibited similar stretched exponential decay, which is a fingerprint for localized exciton emissions. The luminescence lifetimes (τPL) of them were as long as 4-10ns between 8 and 300 K, indicating the reduced wavefunction overlap due to the internal polarization fields. According to the analysis based on the model three-level scheme, little difference was found in the nonradiative lifetimes in the free / extended states between the two MQWs. However, the increase of the combined transfer and radiative lifetime with the increase in temperature from 8 to 300 K in the trapezoidal MQW was suppressed by a factor of 1.5 compared to that in the rectangular one, reflecting the recovery of wavefunction overlap and effectively larger localization depth due to the reduced effective field. As a result, the quantum efficiency of the trapezoidal MQW was improved by 40% compared to that of the rectangular one at 300 K.

    Original languageEnglish
    JournalJapanese Journal of Applied Physics, Part 2: Letters
    Volume42
    Issue number11 B
    Publication statusPublished - 2003 Nov 15

    Fingerprint

    Photoluminescence spectroscopy
    Semiconductor quantum wells
    quantum wells
    photoluminescence
    spectroscopy
    Wave functions
    life (durability)
    radiative lifetime
    profiles
    Quantum efficiency
    Excitons
    Luminescence
    quantum efficiency
    Photoluminescence
    recovery
    excitons
    Polarization
    luminescence
    Recovery
    decay

    Keywords

    • Exciton localization
    • InGaN
    • Piezoelectric field
    • Quantum efficiency
    • Quantum well
    • Recombination dynamics
    • Time-resolved photoluminescence spectroscopy

    ASJC Scopus subject areas

    • Physics and Astronomy (miscellaneous)

    Cite this

    Improved Emission Efficiency in InGaN / GaN Quantum Wells with Compositionally-Graded Barriers Studied by Time-Resolved Photoluminescence Spectroscopy. / Onuma, Takeyoshi; Uchinuma, Yoshimasa; Suh, Eun Kyung; Lee, Hyung Jae; Sota, Takayuki; Chichibu, Shigefusa F.

    In: Japanese Journal of Applied Physics, Part 2: Letters, Vol. 42, No. 11 B, 15.11.2003.

    Research output: Contribution to journalArticle

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    abstract = "Recombination dynamics in InGaN/GaN multiple quantum wells (MQWs) having different well/barrier potential profiles were studied. Time-resolved photoluminescence (TRPL) signals of the MQWs having regular potential profiles (rectangular MQW) and those having the compositionally-graded barriers (trapezoidal MQW) exhibited similar stretched exponential decay, which is a fingerprint for localized exciton emissions. The luminescence lifetimes (τPL) of them were as long as 4-10ns between 8 and 300 K, indicating the reduced wavefunction overlap due to the internal polarization fields. According to the analysis based on the model three-level scheme, little difference was found in the nonradiative lifetimes in the free / extended states between the two MQWs. However, the increase of the combined transfer and radiative lifetime with the increase in temperature from 8 to 300 K in the trapezoidal MQW was suppressed by a factor of 1.5 compared to that in the rectangular one, reflecting the recovery of wavefunction overlap and effectively larger localization depth due to the reduced effective field. As a result, the quantum efficiency of the trapezoidal MQW was improved by 40{\%} compared to that of the rectangular one at 300 K.",
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    AU - Suh, Eun Kyung

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    AU - Sota, Takayuki

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