Monitoring Ultrafast Laser Micro-Excitation and Modification Deep inside GaAs - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès ieee Année : 2021

Monitoring Ultrafast Laser Micro-Excitation and Modification Deep inside GaAs

Monitoring Ultrafast Laser Micro-Excitation and Modification Deep inside GaAs

Résumé

Creating 3D micro/nano-structures inside semiconductors, such as Silicon or GaAs, is a key for numerous advanced applications from microelectronics to integrated photonics, micro-electro-mechanical systems (MEMS) manufacturing. Direct ultrafast laser writing introduces a promising alternative to lithographic methods for this purpose because of its capability with focused infrared beams to precisely induce micro/nano-scale structures. This has already been successfully applied in wide bandgap materials, but recent research indicates more severe difficulties for applications in semiconductors [1-3]. The inherent properties of narrow bandgap and large nonlinear refractive index materials lead to strong deteriorations of the ideal laser focusing conditions that prevents to access high space-time energy localization with the shortest pulses [2]. The nonlinear propagation distortions lead to limited fluence delivery and consequently low-quality writing in most cases, or even to the absence of modifications when femtosecond pulses are used. Accordingly, there is a strong motivation to monitor and optimize the conditions inside semiconductors to achieve high-quality 3D fabrication inside semiconductors. To optimize the process, a first step is to characterize the distortion of the focusing spot. Strong difficulties exist for the measurement because the interaction is under the surface and the dimensions of the laser spot is small, especially in the tight focusing conditions. We propose to image the laser propagation by taking advantage of the photo-emission from the laser-induced free-carriers. Fig. 1a shows the light emission generated by laser focusing inside GaAs materials (similar phenomenon also happens in Silicon). Its shape is similar to the plasma shape measured by ultrafast laser pump-probe shadowgraph (Fig. 1b). By measuring the polarization and spectrum range, the photo-emission is confirmed to be related to radiative recombination. Using a calibration method, we show that its intensity increases linearly with the electron density and thus it can be a useful approach for quantitative analysis of nonlinear ionization inside semiconductors. In addition to 2D images, this method can also be used to reconstruct by a z-scanning 3D distribution of excitations. This offers one more additional dimension for analyses of potentially complex spatial features with non-Gaussian or strongly distorted beams. An example of near-surface plasma induced by looser focusing is shown in Fig. 1c, demonstrating the possibility for 3D imaging.
Fichier principal
Vignette du fichier
CLEOEU2021_AW_HAL.pdf (241.48 Ko) Télécharger le fichier
Origine Fichiers produits par l'(les) auteur(s)

Dates et versions

hal-03373738 , version 1 (11-10-2021)

Identifiants

Citer

Andong Wang, Amlan Das, Jörg Hermann, David Grojo. Monitoring Ultrafast Laser Micro-Excitation and Modification Deep inside GaAs. 2021 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), Jun 2021, Munich, France. pp.1-1, ⟨10.1109/CLEO/Europe-EQEC52157.2021.9542518⟩. ⟨hal-03373738⟩
25 Consultations
72 Téléchargements

Altmetric

Partager

Gmail Mastodon Facebook X LinkedIn More