Simple Preparation of Fluorescent Silicon Nanoparticles from Used Si Wafers

Abstract

A simple way of preparing fluorescent silicon nanoparticles (SiNPs) with a mean diameter of ∼5 nm was demonstrated from used silicon wafers. Anodic etching of used wafers performed in a customized electrochemical cell produced H-terminated, nano- and micropores on the wafer surface, and SiNPs were attained by mechanically crumbling the nano-/microporous Si surface structures on the etched wafers in an ultrasonic bath. The obtained SiNPs were then re-etched in different ratios of HF/HNO3 acid mixture to produce different PL intensities, sizes, and yields. When the particle sizes were decreased by adjusting the experimental conditions (e.g., strength of the acid mixture, reaction time), the PL spectra from etched SiNPs were also shifted from red to blue, indicating the quantum confinement effect from the nanoparticles. Typically, blue-emitting SiNPs were observed with an average diameter of 2.7 nm and a yield of 0.3 mg/cm2 of used wafers. Re-etched SiNPs were dialyzed by a 1K-dialysis membrane for purification and for potential use in bioapplications. The efficient method of preparing fluorescent nanoparticles from used monocrystalline Si wafers was demonstrated with a high production yield. The produced particles showed outstanding physical and chemical properties, indicating the applicability of these materials in semiconductor research and bioapplications.

Sensitive detection of copper ions via ion-responsive fluorescence quenching of engineered porous silicon nanoparticles

“…The PL intensity of UDA-PS NPs is even stronger, with a 10 fold increase in intensity over that of AA-PS NPs. Both AA-PS NPs and UDA-PS NPs exhibit maximum PL intensity at approximately 650 nm and corroborate the rearrangement of surface structure and subsequent promotion of efficient proton emission 19 ; the increased PL of alkyl-passivated PS NPs is most likely due to the quantum confinement effect and defect localization at the Si–SiO 2 interface 26 . Furthermore, the quantum yield (Ф) of UDA-PS NPs is 0.11 when indirectly compared to the value of Rhodamine ( Supporting Fig.…”

“…Given the size-dependent tunable photoluminescence (PL), high quantum yield, broad excitation spectra, low photobleaching, and low toxicity of PS NPs, they thereby present a viable means to increasing the sensitivity of Cu detection 16 17 18 . Various methods have been reported for the synthesis of such PS NPs 9 10 11 12 13 14 15 , including their fabrication from Si wafers via electrochemical wet etching 19 as previously demonstrated by our group. Interestingly, previous studies on PS NPs report that oxide-terminated silicon NPs often experience PL-quenching under a variety of conditions 20 21 22 , in which Cu 2+ can dramatically reduce the quantum efficiency of porous silicon by capturing excited carriers and interrupting radiative recombination processes 23 24 .…”

Silicon Quantum Dot-Based Fluorescent Probe: Synthesis Characterization and Recognition of Thiocyanate in Human Blood

“…Various physical and chemical processes such as electrochemical etching, , sol–gel method, , laser ablation, , thermal annealing, thermal vaporization, and inverse micelle − are available for the synthesis of the SQDs. Among these, though the inverse micelle is robust one, it has two major drawbacks: (i) easy aerial oxidation at room temperature and (ii) water insolubility.…”

Sonofragmentation of Ultrathin 1D Nanomaterials

“…A multitude of methods have been developed to produce such NPs . Top‐down synthesis methods that rely on breaking down bulk materials into smaller fragments can be scalably deployed . However, the method struggles with monodispersity and with percent yield for such small NPs.…”

“…Bottom‐up synthesis methods can effectively assemble small molecule precursors into larger units to create small NPs . However, both methods require harsh chemicals or specialized equipment, out of reach from many end users. Ideally, one could obtain extremely monodisperse NPs of small size and high yield on regular benchtop equipment on site.…”