Laser Induced Breakdown Spectroscopy (LIBS); Intermetallic nanoalloys; Nanocomposites Calibration-free; Quantitative analysis;OXYGEN REDUCTION REACTION; PLASMA-MASS SPECTROMETRY; BIFUNCTIONAL ELECTROCATALYSTS; OXIDE NANOPARTICLES; EVOLUTION REACTIONS; ABLATION SYNTHESIS; CATALYTIC-ACTIVITY; AEROSOL-PARTICLES; ALLOY; COBALT

Intermetallic nanoalloys (NAs) and nanocomposites (NCs) have increasingly gained prominence as efficient catalytic materials in electrochemical energy conversion and storage systems. But their morphology and chemical compositions play critical role in tuning their catalytic activities, and precious metal contents. While advanced microscopy techniques facilitate morphological characterizations, traditional chemical characterizations are either qualitative or extremely involved. In this study, we apply Laser Induced Breakdown Spectroscopy (LIBS) for quantitative compositional analysis of NAs and NCs synthesized with varied elemental ratios by our in-house built pulsed laser ablation technique. Specifically, elemental ratios of binary PtNi, PdCo (NAs) and PtCo (NCs) of different compositions are determined from LIBS measurements employing an internal calibration scheme using the bulk matrix species as internal standards. Morphology and qualitative elemental compositions of the aforesaid NAs and NCs are confirmed from Transmission Electron Microscopy (TEM) images and Energy Dispersive X-ray Spectroscopy (EDX) measurements. LIBS experiments are carried out in ambient conditions with the NA and NC samples drop cast on silicon wafers after centrifugation to increase their concentrations. The technique does not call for cumbersome sample preparations including acid digestions and external calibration standards commonly required in Inductively Coupled Plasma -Optical Emission Spectroscopy (ICP-OES) techniques. Yet the quantitative LIBS results are in good agreement with the results from ICP-OES measurements. Our results indicate the feasibility of using LIBS in future for rapid and in situ quantitative chemical characterizations of wide classes of synthesized NM and NCs.

NANOPARTICLES; AEROSOLS

Intermetallic ternary nanoalloys (NA) have increasingly gained prominence as excellent catalysts. But, their size, morphology and chemical compositions affect their catalytic and interfacial activities significantly. In this study, we present laser-induced breakdown spectroscopy (LIBS) for rapid quantitative elemental composition characterization of ternary NAs with different elemental ratios. Specifically, we use a calibration-free approach with LIBS to estimate the elemental ratios of PtCuCo ternary NAs with various stoichiometric ratios synthesized via our in-house laser ablation synthesis in solution-galvanic replacement reactions (LASiS-GRR) technique. The size and morphology of the samples are determined from transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) measurements. The LIBS quantitative estimations for the NA samples are compared with results from inductively coupled plasma-optical emission spectroscopy (ICP-OES). The elemental ratio results of quantitative LIBS show good agreement with ICP-OES results, while being devoid of any external standard requirements or extensive sample preparations.

SILICON-WAFERS; CRYSTAL-GROWTH; SOLAR-CELL; AEROSOLS; ABLATION; CU(IN,GA)SE-2; TRANSISTORS; CAPACITANCE; THICKNESS; RESIDUES

The current Largest market share and continually growing industry of the semiconductor manufacturing sector in the US demands rapid and cost-effective quality control and characterization of thin film semiconducting materials. To this end, we demonstrate Laser Induced Breakdown Spectroscopy (LIBS) as a facile and effective analytical tool for rapid process-Line characterization of metal-oxide semiconductor (MOS) transistors and capacitors. Specifically, we carry out quantitative LIBS analysis on siLicon oxide (Si02) thin-films of various thicknesses grown by high-temperature moisture-free oxidation on industrial-grade Si wafers. The stoichiometric ratios of oxygen to siLicon ([O]/[Si]) in various SiO2 films are measured by LIBS anaLyses using an internal calibration technique. The results are verified against benchmark anaLyses based on oxide Layer thicknesses and Laser-induced crater profile topographies from eLLipsometry, scanning electron microscopy (SEM), atomic force microscopy (AFM), and profflometry measurements. The stoichiometric ratios of [O]/[Si] calculated from thickness and profflometry measurements are used to compare with our direct LIBS measurements. Our results indicate good agreement between the LIBS and profibmetry calculation results, demonstrating the future capability of LIBS for thin film characterization during their industrial processing.