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doping stopped

CAREER : Ultimate Limits of Dopant Junctions in Nanowires Lincoln Lauhon , Northwestern University, DMR 0449933.

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doping stopped

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  1. CAREER: Ultimate Limits of Dopant Junctions in NanowiresLincoln Lauhon, Northwestern University, DMR 0449933 Control of the doping of semiconductor nanowires is essential to their utilization in nano-enabled device technologies. We have established the ultimate limits on the abruptness of doping junctions in nanowires grown using metal nanoparticle catalysts. A model of nanowire doping has shown that the width of the junction formed when the dopant source is switched is determined by the amount of dopant dissolved in the catalyst- a ‘memory’ effect. The dopant solubility was determined by fitting a dopant decay profile to local dopant concentrations measured quantitatively by atom probe tomography. We concluded that the dopant solubility needs to be reduced to form abrupt junctions- most readily by using metal catalysts that are solid at the growth temperature. nanocatalyst doping stopped doping gradient The decay of phosporous dopant concentration is much longer than the 30n m diameter of the nanowire, indicating that it is not possible to form abrupt dopant junctions in nanowires grown with liquid catalysts.

  2. Undergraduate research project and paperLincoln Lauhon, Northwestern University, DMR 0449933 Zachary Al-Balushi, a Penn State undergraduate from Abu Dhabi, developed an aqueous synthesis of gold-copper oxide core-shell nanoparticles for use as catalysts in the synthesis of size controlled semiconductor nanowires. Through a collaboration with graduate student Justin Connell, in-situ transmission electron microscopy measurements revealed the formation of a gold-copper alloy at the expected temperature of complete miscibility. A manuscript with Zach as co-first author has been drafted, and the nanoparticles are being used for nanowire synthesis on the project. Zach has also presented his research at the Argonne Undergraduate Research Symposium. Gold-copper alloy nanoparticles were synthesized by coating gold nanoparticles in a thin layer of copper oxide and then annealing in vacuum such that the copper dissolves into the gold.

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