Development of the laser processing simulation method

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K05089
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Optical engineering, Photon science
• Research Institution: National Institutes for Quantum and Radiological Science and Technology
• Principal Investigator: Otobe Tomohito 国立研究開発法人量子科学技術研究開発機構, 関西光科学研究所 光量子科学研究部, 主幹研究員(定常) (60421442)
• Co-Investigator(Kenkyū-buntansha): 小林 亮 名古屋工業大学, 工学(系)研究科(研究院), 助教 (70560126)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: フェムト秒レーザー加工 / 時間依存密度汎関数法

Outline of Final Research Achievements

From the distribution of electronic states obtained by SALMON, the density of excited electrons and internal energies were calculated. We made the program to determine the temperature and chemical potential so as to reproduce them in a Fermi-Dirac distribution. Since the energy relaxation between the valence and conduction bands is slower in semiconductors than in each band, the temperatures of electron and hole were treated separately. Using this method, we were able to fit electron and hole with their respective temperatures and chemical potentials to reproduce the results of the principle calculation. We also found that the temperature of electron and hole depend on the excitation process.

Free Research Field

レーザー科学

Academic Significance and Societal Importance of the Research Achievements

モデル計算が主であったフェムト秒レーザー加工の初期過程の解析を，第一原理計算手法と言われる時間依存密度汎関数法とマックスウェル方程式を用いて行った．特に，より疎視的計算手法である確率過程モデルや分子動力学計算と上記手法を繋ぐための温度評価方法を提案した．これら解析手法を用いて，電場強度と電子温度，レーザー波長と加工深さ，バンド構造と電子温度といった様々なパラメータ間の関係性を明らかにすることができた．得られた知見と手法によりフェムト秒レーザー加工の理解及び予測に大きく寄与したものと思われる．