Silicon nanoparticles with UV range photoluminescence synthesized through cryomilling induced phase transformation and e
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Silicon nanoparticles with UV range photoluminescence synthesized through cryomilling induced phase transformation and etching Hemaprabha Elangovan1, Sanchita Sengupta2, Ravishankar Narayanan3, and Kamanio Chattopadhyay1,4,* 1
Interdisciplinary Centre for Energy Research, Indian Institute of Science, Bangalore 560012, India Department of Chemical Sciences, Indian Institute of Science Education and Research, Mohali 140306, India 3 Materials Research Centre, Indian Institute of Science, Bangalore 560012, India 4 Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, India 2
Received: 3 June 2020
ABSTRACT
Accepted: 19 September 2020
We report silicon nanoparticles with a particle size distribution of * 80 nm (mode) through controlled impact mode cryomilling of semiconductor grade silicon wafers at a temperature of 200 K under argon atmosphere. The transmission microscopic characterization of these particles establishes a partial transformation of the crystalline silicon into an amorphous phase yielding a two-phase microstructure for each of the particles. A high-speed imaging technique is utilized to understand the effect of impact energy (and milling intensity) on the phase transformation during milling. In a further development, etching of the two-phase nanocomposites leads to the dissolution of the amorphous phase yielding free nanoparticle of * 2 nm size that exhibit UV range photoluminescence with potential for sensors and other optical applications.
Published online: 6 October 2020
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Springer Science+Business
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Introduction Silicon in bulk form is an indirect bandgap material, and the tunable optoelectronic applications are achieved when its size reduces to less than that of Bohr radius (5 nm for silicon) [1, 2]. The interest in silicon nanostructures (quantum dots, nanocrystals (NCs), porous particles, composite particles, etc.) increased significantly, after the discovery of the Handling Editor: Pedro Camargo.
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https://doi.org/10.1007/s10853-020-05374-z
bright red–orange fluorescence from nanoporous silicon, by Canham et al. [3]. Among several others, notable applications including sensors [4, 5], optical devices [6, 7], bioimaging and biosensing [8], solar cells [9, 10], batteries [11–13] have been demonstrated using silicon nanoparticles because of its exciting optoelectronic properties, abundancy, cost effectiveness, biocompatibility, and compatibility with the well-established silicon microelectronics technology [14–19]. Theoretical calculations suggest a similar
1516 trend in Si nanoparticles with different sizes due to change in the nature of the silicon band [1, 20, 21]. Further, as an additional benefit, tuning the surface termination of the silicon nanoparticles results in interesting optical properties [22, 23]. For preparation of silicon nanoparticles, a variety of techniques such as pulsed laser deposition [24–28], decomposition of silane precursors [29–31], solution-
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