2001 Fiscal Year Final Research Report Summary
Theoretical analysis of lasing characteristics of stacked lnGaN quantum dot lasers from atomic scale
| Project/Area Number |
12650004
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SAITO Toshio University of Tokyo, CCR, Research associate, 国際・産学共同研究センター, 助手 (90170513)
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| Co-Investigator(Kenkyū-buntansha) |
ARAKAWA Yasuhiko University of Tokyo, RCAST, Professor, 先端科学技術研究センター, 教授 (30134638)
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| Project Period (FY) |
2000 – 2001
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| Keywords | GaN / lnGaN / quantum dot / electronic structure / fight-binding method / piezoelectric effect / Stark effect / wave function overlap |
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| Research Abstract |
We have analyzed the electronic structures of ln_<0.2>Ga_<0.8>N pyramidal quantum dots (QDs) in a GaN barrier layer using a polarization-potential dependent sp^3 tight-binding method. A valence-force-field method using the Keating potential was used for the strain and atom-position calculations. For the QD with the diameter 86.4 A, height of 20.8 A, and facet inclination angle of 30 degree, the maximum piezoelectric field is calculated to be1.64 MV/cm. The energy gap shows a red shift of 0.100 eV due to the quantum-confined Stark effect. The field causes a spatial separation of the electron and hole wave functions in the QD. The number of electron-hole pairs, which can screen the field totally, is estimated as a function of the diameter. We find that 13 electron-hole pairs are required for the complete field screening for the QD with the diameter 86.4 A. In experiments by Damilano et al., the photoluminescence peak energy, E_<PL>, of 2.71 eV (at room temperature) was measured for the MBE-grown In_<0.2>Ga_<0.8>N QDs with the similar QD size ; diameter = 100 A, heitht = 20 A. Eg = 2.706 eV for the pyramidal QD is in better agreement with the measured energy, E_<PL> = 2.71 eV, than Eg = 2.502 eV for the prismatic QD.
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[Publications] T. Saito, T. Someya, K. Tachibana, S. Ishida, O. Moriwaki, and Y. Arakawa: ""Formation of InGaN Quantum Dots : NOCVD Growth and Electronic Structures," Proc. of 3rd SANKEN Int"Symp. on Advanced Nanoelectronics : Devices, Materials, and Computing, Osaka, Japan, (Memoirs of The Institute of Scientific and Industrial Research, Osaka, University, Special Issue. Vol. 57. 167 (2000)
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