A theoretical model of the femtosecond laser ablation of semiconductors considering inverse bremsstrahlung absorption

The mechanism of the femtosecond laser ablation of semiconductors is investigated. The collision pro cess of free electrons in a conduction band is depicted by the test particle method, and a theoretical model of nonequilibrium electron transport on the femtosecond timescale is proposed based on the...

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Bibliographic Details
Published in:Journal of semiconductors 2012-04, Vol.33 (4), p.144-148
Main Author: 林晓辉 张赤斌 任维松 蒋书运 欧阳全会
Format: Article
Language:English
Subjects:
Ablation
Bremsstrahlung
Femtosecond
Inverse
Laser ablation
Lasers
Mathematical models
Semiconductors
半导体
吸收系数
模型
激光烧蚀
电子分布函数
电子碰撞
输运理论
飞秒激光
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Summary:The mechanism of the femtosecond laser ablation of semiconductors is investigated. The collision pro cess of free electrons in a conduction band is depicted by the test particle method, and a theoretical model of nonequilibrium electron transport on the femtosecond timescale is proposed based on the FokkerPlanck equa tion. This model considers the impact of inverse bremsstrahlung on the laser absorption coefficient, and gives the expressions of electron drift and diffusion coefficients in the presence of screened Coulomb potential. Numerical simulations are conducted to obtain the nonequilibrium distribution function of the electrons. The femtosecond laser ablation thresholds are then calculated accordingly, and the results are in good agreement with the experimental results. This is followed by a discussion on the impact of laser parameters on the ablation of semiconductors.
ISSN:1674-4926
DOI:10.1088/1674-4926/33/4/046002