Fabrication of Hierarchical Sapphire Nanostructures using Ultrafast Laser Induced Morphology Change

Fuente: arXiv
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Autori principali: Cheung, Joshua, Chien, Kun-Chieh, Sokalski, Peter, Shi, Li, Chang, Chih-Hao
Natura: Preprint
Pubblicazione: 2024
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author Cheung, Joshua
Chien, Kun-Chieh
Sokalski, Peter
Shi, Li
Chang, Chih-Hao
author_facet Cheung, Joshua
Chien, Kun-Chieh
Sokalski, Peter
Shi, Li
Chang, Chih-Hao
contents Sapphire is an attractive material in photonic, optoelectronic, and transparent ceramic applications that stand to benefit from surface functionalization effects stemming from micro/nanostructures. Here we investigate the use of ultrafast lasers for fabricating nanostructures in sapphire by exploring the relationship between irradiation parameters, morphology change, and selective etching. In this approach an ultrafast laser pulse is focused on the sapphire substrate to change the crystalline morphology to amorphous or polycrystalline, which is characterized by examining different vibrational modes using Raman spectroscopy. The irradiated regions are then removed using a subsequent wet etch in hydrofluoric acid. Laser confocal measurements conducted before and after the etching process quantify the degree of selective etching. The results indicate that a threshold laser pulse intensity is required for selective etching to occur. This process can be used to fabricate hierarchical sapphire nanostructures over large areas with enhanced hydrophobicity, which exhibits an apparent contact angle of 140 degrees and a high roll-off angle that are characteristic of the rose petal effect. Additionally, the fabricated structures have high broadband diffuse transmittance of up to 81.8% with low loss, which can find applications in optical diffusers. Our findings provide new insights into the interplay between the light-matter interactions, where Raman shifts associated with different vibrational modes can be used as a predictive measure of selective etching. These results advance the development of sapphire nanostructure fabrication, which can find applications in infrared optics, protective windows, and consumer electronics.
format Preprint
id arxiv_https___arxiv_org_abs_2411_11817
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Fabrication of Hierarchical Sapphire Nanostructures using Ultrafast Laser Induced Morphology Change
Cheung, Joshua
Chien, Kun-Chieh
Sokalski, Peter
Shi, Li
Chang, Chih-Hao
Materials Science
Sapphire is an attractive material in photonic, optoelectronic, and transparent ceramic applications that stand to benefit from surface functionalization effects stemming from micro/nanostructures. Here we investigate the use of ultrafast lasers for fabricating nanostructures in sapphire by exploring the relationship between irradiation parameters, morphology change, and selective etching. In this approach an ultrafast laser pulse is focused on the sapphire substrate to change the crystalline morphology to amorphous or polycrystalline, which is characterized by examining different vibrational modes using Raman spectroscopy. The irradiated regions are then removed using a subsequent wet etch in hydrofluoric acid. Laser confocal measurements conducted before and after the etching process quantify the degree of selective etching. The results indicate that a threshold laser pulse intensity is required for selective etching to occur. This process can be used to fabricate hierarchical sapphire nanostructures over large areas with enhanced hydrophobicity, which exhibits an apparent contact angle of 140 degrees and a high roll-off angle that are characteristic of the rose petal effect. Additionally, the fabricated structures have high broadband diffuse transmittance of up to 81.8% with low loss, which can find applications in optical diffusers. Our findings provide new insights into the interplay between the light-matter interactions, where Raman shifts associated with different vibrational modes can be used as a predictive measure of selective etching. These results advance the development of sapphire nanostructure fabrication, which can find applications in infrared optics, protective windows, and consumer electronics.
title Fabrication of Hierarchical Sapphire Nanostructures using Ultrafast Laser Induced Morphology Change
topic Materials Science
url https://arxiv.org/abs/2411.11817