Role of localized quantum well excitons in InGaN quantum well structure correlated with microstructural analysis

S. F. Chichibu, Takayuki Sota, S. Nakamura

研究成果: Conference contribution

抄録

In xGa 1-xN multiple-quantum-well laser diode structure, which lased at 405 nm, was shown to have atomically-flat interfaces between each layer. Nanometer-probe compositional analysis showed that InN mole fraction, x, in the wells and barriers are approximately 6 % and 2 %, respectively, which agreed with the result obtained from high-resolution x-ray diffraction measurement. The Stokes-like shift (SS) at 300 K was 49 meV, being approximately 65 % of the luminescence linewidth. The localization depth, E 0, of quantum-well (QW) excitons as estimated to be 35 meV at 300 K though the compositional fluctuation in the well was as small as 1 % or less (detection limit) within adjacent 20-30 nm lateral length scale. Since the well thickness fluctuation is insufficient to reproduce SS or E 0, effective bandgap inhomogeneity is attributed to be due to large bandgap bowing in InGaN. The spontaneous emission was thus assigned as being due to the recombination of QW excitons weakly localized in exponential tail-type potential minima in the QW. The size of localization is smaller than the quantum-disk [M. Sugawara, Phys. Rev. B 51, 10743 (1995)]-size. Such small bandgap inhomogeneity can be leveled by injecting high density carriers under lasing conditions, which can explain the general experimental finding that the quantum efficiency decreases with increasing carrier density in InGaN QW devices due to free carrier trapping into threading dislocations.

元の言語English
ホスト出版物のタイトルMaterials Research Society Symposium - Proceedings
編集者C Wetzel, M Shur, U Mishra, B Gil, K Kishino
639
出版物ステータスPublished - 2001
外部発表Yes
イベントGaN and Related Alloys 2000 - Boston, MA, United States
継続期間: 2000 11 272000 12 1

Other

OtherGaN and Related Alloys 2000
United States
Boston, MA
期間00/11/2700/12/1

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Excitons
Semiconductor quantum wells
Energy gap
Carrier concentration
Bending (forming)
Quantum well lasers
Spontaneous emission
Quantum efficiency
Linewidth
Semiconductor lasers
Luminescence
Diffraction
LDS 751
X rays

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

これを引用

Chichibu, S. F., Sota, T., & Nakamura, S. (2001). Role of localized quantum well excitons in InGaN quantum well structure correlated with microstructural analysis. : C. Wetzel, M. Shur, U. Mishra, B. Gil, & K. Kishino (版), Materials Research Society Symposium - Proceedings (巻 639)

Role of localized quantum well excitons in InGaN quantum well structure correlated with microstructural analysis. / Chichibu, S. F.; Sota, Takayuki; Nakamura, S.

Materials Research Society Symposium - Proceedings. 版 / C Wetzel; M Shur; U Mishra; B Gil; K Kishino. 巻 639 2001.

研究成果: Conference contribution

Chichibu, SF, Sota, T & Nakamura, S 2001, Role of localized quantum well excitons in InGaN quantum well structure correlated with microstructural analysis. : C Wetzel, M Shur, U Mishra, B Gil & K Kishino (版), Materials Research Society Symposium - Proceedings. 巻. 639, GaN and Related Alloys 2000, Boston, MA, United States, 00/11/27.
Chichibu SF, Sota T, Nakamura S. Role of localized quantum well excitons in InGaN quantum well structure correlated with microstructural analysis. : Wetzel C, Shur M, Mishra U, Gil B, Kishino K, 編集者, Materials Research Society Symposium - Proceedings. 巻 639. 2001
Chichibu, S. F. ; Sota, Takayuki ; Nakamura, S. / Role of localized quantum well excitons in InGaN quantum well structure correlated with microstructural analysis. Materials Research Society Symposium - Proceedings. 編集者 / C Wetzel ; M Shur ; U Mishra ; B Gil ; K Kishino. 巻 639 2001.
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abstract = "In xGa 1-xN multiple-quantum-well laser diode structure, which lased at 405 nm, was shown to have atomically-flat interfaces between each layer. Nanometer-probe compositional analysis showed that InN mole fraction, x, in the wells and barriers are approximately 6 {\%} and 2 {\%}, respectively, which agreed with the result obtained from high-resolution x-ray diffraction measurement. The Stokes-like shift (SS) at 300 K was 49 meV, being approximately 65 {\%} of the luminescence linewidth. The localization depth, E 0, of quantum-well (QW) excitons as estimated to be 35 meV at 300 K though the compositional fluctuation in the well was as small as 1 {\%} or less (detection limit) within adjacent 20-30 nm lateral length scale. Since the well thickness fluctuation is insufficient to reproduce SS or E 0, effective bandgap inhomogeneity is attributed to be due to large bandgap bowing in InGaN. The spontaneous emission was thus assigned as being due to the recombination of QW excitons weakly localized in exponential tail-type potential minima in the QW. The size of localization is smaller than the quantum-disk [M. Sugawara, Phys. Rev. B 51, 10743 (1995)]-size. Such small bandgap inhomogeneity can be leveled by injecting high density carriers under lasing conditions, which can explain the general experimental finding that the quantum efficiency decreases with increasing carrier density in InGaN QW devices due to free carrier trapping into threading dislocations.",
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AB - In xGa 1-xN multiple-quantum-well laser diode structure, which lased at 405 nm, was shown to have atomically-flat interfaces between each layer. Nanometer-probe compositional analysis showed that InN mole fraction, x, in the wells and barriers are approximately 6 % and 2 %, respectively, which agreed with the result obtained from high-resolution x-ray diffraction measurement. The Stokes-like shift (SS) at 300 K was 49 meV, being approximately 65 % of the luminescence linewidth. The localization depth, E 0, of quantum-well (QW) excitons as estimated to be 35 meV at 300 K though the compositional fluctuation in the well was as small as 1 % or less (detection limit) within adjacent 20-30 nm lateral length scale. Since the well thickness fluctuation is insufficient to reproduce SS or E 0, effective bandgap inhomogeneity is attributed to be due to large bandgap bowing in InGaN. The spontaneous emission was thus assigned as being due to the recombination of QW excitons weakly localized in exponential tail-type potential minima in the QW. The size of localization is smaller than the quantum-disk [M. Sugawara, Phys. Rev. B 51, 10743 (1995)]-size. Such small bandgap inhomogeneity can be leveled by injecting high density carriers under lasing conditions, which can explain the general experimental finding that the quantum efficiency decreases with increasing carrier density in InGaN QW devices due to free carrier trapping into threading dislocations.

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