Direct Femtosecond Laser Fabrication of Chemically Functionalized Ultra-Black Textures on Silicon for Sensing Applications.

Yulia Borodaenko,Sergei A Kulinich,Aleksandr Mironenko,Mikhail Tutov,Stanislav Gurbatov,Alexey Zhizhchenko,Aleksandr Kuchmizhak

doi:10.3390/nano11020401

Abstract

Here, we present the single-step laser-assisted fabrication of anti-reflective hierarchical surface textures on silicon locally functionalized with a photoluminescent (PL) molecular nanolayer. Using femtosecond-laser ablation of commercial crystalline Si wafers placed under a layer of a solution containing rhodamine 6G (R6G) a triethoxysilyl derivative, we fabricated ordered arrays of microconical protrusions with self-organized nanoscale surface morphology. At the same time, the laser-induced temperature increase facilitated surface activation and local binding of the R6G derivative to the as-fabricated nanotextured surface. The produced dual-scale surface textures showed remarkable broadband (visible to near-IR) light-absorbing properties with an averaged reflectivity of around 1%, and the capping molecular nanolayer demonstrated a strongly enhanced PL yield. By performing a pH sensing test using the produced nanotextured substrate, we confirmed the retention of sensory properties of the molecules attached to the surface and validated the potential applicability of the high-performing liquid-assisted laser processing as a key technology for the development of innovative multifunctional sensing devices in which the textured substrate (e.g., ultra-black semiconductor) plays a dual role as a support and PL signal amplifier.

Highlights

IntroductionSilicon (Si) presents an earth-abundant element, which as a semiconductor that exhibits remarkable optoelectronic and optical properties
With no loss in generality, to illustrate the key idea of this paper, here we considered Si processing at κ = 1 KHz and ν = 0.5 mm/s, and only the pulse energy
Each surface area with an overall lateral size of 200 × 200 μm2 was first processed following a snake-like trajectory along one direction; and the textured area was scanned again along the orthogonal direction while preserving the same p (Figure 1b)

Summary

Introduction

Silicon (Si) presents an earth-abundant element, which as a semiconductor that exhibits remarkable optoelectronic and optical properties All this makes it extremely important for the realization of photodetectors, solar cells, micro-electronic devices and optical sensors [6,7,8,9,10,11,12]. In this respect, the rapidly growing interest in the realization of various devices stimulates the search for efficient and simple approaches for the surface engineering of silicon-based semiconductor materials

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Conclusion