2018 Fiscal Year Research-status Report
Searching new operation area for QCL by Gain Mapping using NEGF
| Project/Area Number |
18K04251
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| Research Institution | Institute of Physical and Chemical Research |
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Principal Investigator |
Yun Joosun 国立研究開発法人理化学研究所, 開拓研究本部, 基礎科学特別研究員 (30817359)
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| Co-Investigator(Kenkyū-buntansha) |
平山 秀樹 国立研究開発法人理化学研究所, 開拓研究本部, 主任研究員 (70270593)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | NEGF / QCL / GaN / AlGaN / GaAs / AlGaAs |
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| Outline of Annual Research Achievements |
We found that the polarization-related carrier scattering processes such as dipole scattering, polarization Coulomb field scattering and polarization surface roughness scattering should be considered for the correct design and simulation of GaN/AlGaN QCL structures. Therefore, our proposed structures must be upgraded by including spectral broadening originated from these polarization-related scattering. Since the commercial software supports only traditional scattering mechanisms such as polar optical phonon (POP), acoustic phonon, interface roughness, electron-electron scattering and impurity scattering, we accelerated to develop our own NEGF simulator in order to progress our project to the right direction. We adopted the calculation algorithm of Appl. Phys. Rev. 1, 011307 (2014) into the new simulator. After finishing the development, the software was moved to the supercomputer system in RIKEN (HOKUSAI BigWaterfall) after hybrid parallelization based on OpenMP and MPI (Message Passing Interface). The validity of this new simulator was secured by comparing with several previously published experimental reports for GaAs/AlGaAs QCLs. Also, gain-mapping was performed for these structures by utilizing the new developed software as a test process. After that, we have been designing self-energies for dipole scattering in AlGaN material system as a first. We expect that the improved and more reasonable design for GaN-based QCLs will be available soon. Also, the influence of polarization-related scattering processes in quantum transport of GaN/AlGaN QCLs may be unveiled.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
Our plan was slightly delayed after we find the importance of polarization-related scattering mechanisms in GaN/AlGaN devices. After we were noticed to those, we accelerated to develop NEGF software by ourselves since the Nextnano's commercial software does not support polarization-related scattering mechanisms currently. Since the self-energy models for these scattering processes in GaN/AlGaN have not been reported yet, we have been developing new self-energy models by ourselves. We expect several fruitful achievements from this year.
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| Strategy for Future Research Activity |
Future plan is like follow.
1. Design of self-energies for dipole scattering and polarization surface roughness scattering.
2. Structural design and gain-mapping of several GaN-based QCL structures in order to find new operational frequency and temperature range
4. Growth and fabrication of designed structures
5. Measurement of fabricated QCL devices
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| Remarks |
We have developed a quantum transport simulator adopting non-equilibrium Green's function based on real space representation. Its development was finished recently and moved to a supercomputer.
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