Optical Properties of Silicon Nano-Structures: Metal Assisted Chemical Etching and a Two-Stage Ion Implantation
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ORIGINAL PAPER
Optical Properties of Silicon Nano-Structures: Metal Assisted Chemical Etching and a Two-Stage Ion Implantation Gayatri Sahu 1
&
Gunadhor S. Okram 1
Received: 26 May 2020 / Accepted: 5 September 2020 # Springer Nature B.V. 2020
Abstract Two different methods of dual metal ion implantation technique and metal-assisted chemical etching are used to fabricate silicon nanostructures. Raman scattering and photoluminescence techniques have been employed to study the optical properties of formed Si nanostructures. Scanning Electron Microscopy images indicate the change in the surface morphology of Si nanowires with respect to the etching time. Dual ion implantation sample and metal-assisted chemical etching, prepared for 45 min exhibit similar optical properties. With a possible mechanism of their formation at room temperature, synthesizability of Si NWs in large scale for commercial purposes is discussed. It is expected that these Si NWs have got potential applications in optoelectronics, photonics and sensors. Keywords Silicon nanostructures . Ion implantation . Metal assisted chemical etching . Raman scattering . Photoluminescence
1 Introduction Though Silicon is the backbone of electronics industry, because of its indirect band gap nature it has got restricted applications in the field of optoelectronics. Bulk crystalline Silicon (c-Si) is a poor light emitter at room temperature. Reducing the size of the particles to nanoscale, it has been observed that Si nanoparticles/porous Si emit light in visible range [1, 2]. This has attracted lots of attention in different fields of research having various applications like solar cells [3], optoelectronics [4, 5], field emission [6] and sensors [7]. Availability in high purity, natural abundance, low cost and non-toxicity have made this material highly attractive for various applications (other than the microelectronics) including some optical ones [8, 9]. Along with the above-mentioned properties, additional luminescence property makes Si nanostructures a smart material. It is well known that particle sizes below the excitonic Bohr radius (for Si, a B = 4.3 nm), Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12633-020-00695-9) contains supplementary material, which is available to authorized users. * Gayatri Sahu [email protected]; [email protected] 1
UGC-DAE Centre for Scientific Research Indore, University Campus, Khandwa Road, Indore, Madhya Pradesh 452001, India
nanostructures show quantum confinement effect [10, 11]. Depending on the size of Si nanostructure, it has been observed that it emits in a wide range of wavelengths i.e. from UV to near infrared region [12–16]. The band gap (indirect) of bulk Si is 1.1 eV, but the electronic structure of bulk Si has a direct band gap of 3.3 eV, at the center of the Brillouin zone (the Γ-point) [12]. This is nearly 2 eV higher in energy than that of the absolute minima of the conduction band [17]. Different methods have been adopted for synthesis of Si nan
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