High-density excitation effect on photoluminescence in ZnO nanoparticles

• Suzuki, Keigo

• Inoguchi, Masashi

• Fujita, Koji

• Murai, Shunsuke

• Tanaka, Katsuhisa

• Tanaka, Nobuhiko

• Ando, Akira

• Takagi, Hiroshi

抄録

In this study, photoluminescence PL under high excitation intensity as a function of crystalline size was systematically investigated through ZnO nanocrystalline films prepared by spin-coating a colloidal solution of ZnO nanoparticles obtained using the microemulsion method. Annealing of the films at 723, 633, and 593 K allowed us to tune the crystalline radius R. PL studies distinguished different regimes of crystalline size according to the ratio of R to the effective Bohr radius aB R/aB. For the sample annealed at 723 K R/aB=7.2 , the peak of stimulated emission due to the exciton-exciton collisions appeared on the low-energy side of the exciton emission with an increase in excitation intensity. A further increase in excitation intensity eventually resulted in the occurrence of an electron-hole plasma EHP accompanied by consequent band gap renormalization, which indicates that high excitation intensity provokes the dissociation of excitons. For the sample annealed at 633 K R/aB=4.7 , the stimulated emission was observed while the transition to EHP was obscure. For the sample annealed at 593 K R/aB=2.1 , only emissions due to the recombination of the electron-hole pair were observed, and stimulated emission did not appear even when the excitation intensity was increased. The transition from free-exciton emission to donor-bound exciton emission was observed in temperature dependence of PL only for the sample with R/aB=7.2. The origin of annihilation of the stimulated emission with a size reduction is discussed based on nonradiative Auger recombination.

収録刊行物

• JOURNAL OF APPLIED PHYSICS

  JOURNAL OF APPLIED PHYSICS 107 (12), 2010-06

  AMER INST PHYSICS

詳細情報

• CRID: 1050845760651076992
• NII論文ID: 120003386588
• NII書誌ID: AA00693547
• ISSN: 00218979
• HANDLE: 2433/147189
• 本文言語コード: en
• 資料種別: journal article
• データソース種別:
  • IRDB
  • CiNii Articles