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Compared to traditional methods, femtosecond lasers with their very short pulse durations offer superior precision. Complex 3D structures as well as non-conventional shapes can be obtained.

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Femtosecond processing of GaAs in ambient air and water environment

Processing semiconductor materials such as Gallium Arsenide (GaAs) using ultrashort laser pulses presents unique challenges due to heat accumulation and the need for precise, high-quality modifications. Femtosecond lasers are particularly well-suited for this task, offering minimal thermal impact and high precision.

In a comprehensive study, the ablation of GaAs was investigated in both ambient air and water environments. The study utilized a Femtolux 30, operating at a wavelength of 1030 nm, pulse durations of 900 fs and at repetition rates were tested of 10, 50, and 200 kHz. By ablating trenches on the sample surface in different environments it was observed that usage of water results in increase in trench depth from 58 um to 105 um. Also, due to water environment the ablation debris redeposition width was reduced from 34 um to 7.6 um, essentially leading to higher quality processing. Overall, the study showcased that water environment is beneficial in processing GaAs substrates with a femtosecond laser source.

Groove formation in GaAs in water environment.

Groove formation in GaAs in water environment.

Courtesy of FMTC.

GaAs laser ablation parameters for trench milling in water

Regime No.Average laser powerPulse repetition rateScanning speedNumber of scansFluenceHatchNumber of lines in scanTrench depth
10.4 W10 kHz50 mm/s1413.1 J/cm210 µm11105 µm
22 W50 kHz250 mm/s1413.1 J/cm210 µm1199 µm
38 W200 kHz1000 mm/s1413.1 J/cm210 µm1175 µm
Regime No.Average laser powerPulse repetition rateScanning speedNumber of scansFluenceHatchNumber of lines in scanTrench depth

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