3-D Atomic-Scale Mapping of Manganese Dopants in Lead Sulfide Nanowires

Abstract

Dopants in nanowires, whether intentional or unintentional, can ultimately control the material’s properties and, therefore, need to be understood on the atomic scale. We study vapor–liquid–solid grown manganese-doped lead sulfide nanowires by atom-probe tomography for the first time for lead salt materials. The three-dimensional chemical concentration maps at the atomic scale demonstrate a radial distribution profile of Mn ions, with a concentration of only 0.18 and 0.01 at. % for MnCl2 and Mn-acetate precursors, respectively. The ability to characterize these small concentrations of dopant atoms in Pb1–x Mn x S nanowires (x = 0.0036 and 0.0002), important for spintronic and thermoelectric devices, sets a platform for similar analyses for all nanostructures. First-principles calculations confirm that Mn atoms substitute for Pb in the PbS structure.

Paramagnetic, Near‐Infrared Fluorescent Mn‐Doped PbS Colloidal Nanocrystals

“…The nanocrystals are optically active at room temperature in the technologically important biological window between 1.2 μ m and 0.8 μ m; also, the Mn atoms imprint the nanoparticles with paramagnetic properties. Preliminary cytoxicity studies show that the exposure of human cell lines to the nanoparticles at concentrations up to 0.2 mg mL −1 does not induce any adverse effect, thus providing guidelines on safe doses for further toxicology studies and future applications in medical imaging.Our Mn-doped PbS nanocrystals in an aqueous solution differ from previously reported nanostructures based on PbS nanowires [ 10,11 ] and PbS nanocrystals in glass matrices [ 12,13 ] or in organic solvents. [ 14 ] To synthesize the Mn-doped PbS nanoparticles, we prepared a Pb 2+ precursor solution containing 2.5 × 10 −4 mol of lead acetate Pb(CH 3 COO) 2 , 1.5 × 10 −3 mol of thioglycerol (TGL) and 5 × 10 −4 mol of dithioglycerol (DTG) in 15 mL of deionized water, where the thiols act as capping agents.…”

“…Our Mn‐doped PbS nanocrystals in an aqueous solution differ from previously reported nanostructures based on PbS nanowires and PbS nanocrystals in glass matrices or in organic solvents . To synthesize the Mn‐doped PbS nanoparticles, we prepared a Pb 2+ precursor solution containing 2.5 × 10 −4 mol of lead acetate Pb(CH 3 COO) 2 , 1.5 × 10 −3 mol of thioglycerol (TGL) and 5 × 10 −4 mol of dithioglycerol (DTG) in 15 mL of deionized water, where the thiols act as capping agents .…”

Modern Focused-Ion-Beam-Based Site-Specific Specimen Preparation for Atom Probe Tomography

“…Lift-out-type strategies for NW preparation have been reported as well. For NWs with suitable dimensions, individual NWs can be extracted by cutting or plucking the NWs from the host substrate and attaching them to carrier tips (Agrawal et al, 2011; Eichfeld et al, 2012; Isheim et al, 2012; Sanford et al, 2014; Qu et al, 2015). Although care must be taken to prevent damaging exposure, to any ROI, by the ion beam during the NW cutting operation and subsequent aligning to a carrier tip, many successful analyses have been reported.…”

Atomic-scale tomography of semiconductor nanowires

“…Therefore, accurate atomic characterization of these nanowires is essential for the applications in thermoelectrics. Thereafter, Isheim [82] initiated the APT characterization on Lead Sulfide nanowires with tiny Mn doping, which could not be detected by other techniques. His results shown in Fig.…”