| 研究実績の概要 |
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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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
3: やや遅れている
理由
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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