A new geometrical approach for rapid LED processing by using femtosecond laser

Reklaitis, I.; Grinys, Tomas; Tomašiūnas, R.; Puodžiūnas, Tomas; Mažulė, Lina; Sirutkaitis, Valdas; Lin, Ching−Fuh; Yang, C. C.

doi:10.1016/j.optlaseng.2015.05.002

Cited by 3 publications

(1 citation statement)

References 23 publications

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“…These properties make the material a prime choice for many applications. For example, its chemical and physical properties are exploited in the field of silicon-on-sapphire devices and gallium nitride light emitting diodes (LEDs) [2][3][4][5]. For its transparency and hardness, sapphire is utilized in smartphones or watches [6][7][8], and for its optical properties it is also suitable for applications in the field of photonics [9,10].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of microstructures in the bulk and on the surface of sapphire by anisotropic selective wet etching of laser-affected volumes

Capuano

Berenschot²,

Tiggelaar³

et al. 2022

J. Micromech. Microeng.

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In this paper a processing technique for sapphire is presented which combines laser-induced amorphization and subsequent selective wet etching of amorphized sapphire as well as anisotropic wet etching of single-crystalline sapphire (α-Al2O3). Using this technique, microstructures can be realized on the surface and in the bulk of sapphire substrates. By focusing ultra-short laser pulses inside sapphire, its structure can be transformed from crystalline into amorphous. The modified material can be selectively removed using etchants, such as hydrofluoric acid (HF) or potassium hydroxide (KOH), solely dissolving the amorphized part. In this work, however, an etchant consisting of a standard solution of sulphuric acid and phosphoric acid (96 vol% H2SO4 : 85 vol% H3PO4, 3:1 vol%) at 180 °C is utilized. This method allows the realization of structures which are impossible to achieve when using conventional etchants which solely dissolve the amorphized sapphire. Ultrashort pulsed laser irradiation (230 fs) is used in this study as starting point for the subsequent anisotropic etching to form microstructures on the surface or in the bulk of sapphire that are terminated by characteristic crystal planes. In particular, the appearance of etching-induced patterns formed by stacks of rhombohedra is shown for structures below the surface, whereas triangular pits are achieved in surface processing.

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