Nano Archive

Band-filling of solution-synthesized CdS nanowires

Puthussery, James and Lan, Aidong and Kosel, Thomas H. and Kuno, Masaru (2008) Band-filling of solution-synthesized CdS nanowires. ACS NANO, 2 (2). pp. 357-367.

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The band edge optical characterization of solution-synthesized CdS nanowires (NWs) is described. Investigated wires are made through a solution-liquid-solid approach that entails the use of low-melting bimetallic catalyst particles to seed NW growth. Resulting diameters are approximately 14 nm, and lengths exceed 1 mu m. Ensemble diameter distributions are similar to 13%, with corresponding intravvire diameter variations of similar to 5%. High-resolution transmission electron micrographs show that the wires are highly crystalline and have the wurtzite structure with growth along at least two directions: [00011 and [10 vertical bar$$10]. Band edge emission is observed with estimated quantum yields between similar to 0.05% and 1%. Complementary photoluminescence excitation spectra show structure consistent with the linear absorption. Carrier cooling dynamics are subsequently examined through ensemble lifetime and transient differential absorption measurements. The former reveals unexpectedly long band edge decays that extend beyond tens of nanoseconds. The latter indicates rapid intraband carrier cooling on time scales of 300-400 fs. Subsequent recovery at the band edge contains significant Auger contributions at high intensities which are usurped by other, possibly surface-related, carrier relaxation pathways at lower intensities. Furthermore, an unusual intensity-dependent transient broadening is seen, connected with these long decays. The effect likely stems from band-filling on the basis of an analysis of observed spectral shifts and line widths.

Item Type:Article
Uncontrolled Keywords:CdS; nanowire; one-dimensional; solution-liquid-solid; band edge emission; transient differential absorption spectroscopy; Auger; band-filling many; body; band gap renormalization
Subjects:Material Science > Functional and hybrid materials
Physical Science > Nano objects
Material Science > Nanochemistry
ID Code:455
Deposited By:Farnush Anwar
Deposited On:03 Dec 2008 16:05
Last Modified:20 Jan 2009 15:48

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