Supersonic Nanocrystal Deposition for Nanostructured Materials
Abstract
We experimentally demonstrate the large scale production and controlled collection of metal and semiconductor nanocrystals by laser ablation of microparticles entrained at high density in a flowing aerosol. For silver, produced nanocrystals exhibit bimodal, log-normal size distributions. Mean particle sizes are controlled from 3-16 run by varying the type and pressure of carrier gas as well as laser fluence. For collection, a micronozzle orifice (d = 200 micrometers) accelerates nanocrystals through a sonic jet into a vacuum chamber for deposition onto a room temperature substrate. We describe two regimes of deposition that depend on the nanocrystal's energy per atom on impact. Soft landings (E < < 1 eV/atom) preserve the individual particle properties such as size and shape. Low energy impaction is demonstrated for CdSe in an argon carrier gas. The CdSe nanoclusters remain crystalline upon deposition and display visible photoluminescence. At higher particle impaction velocities (E ^ 0.3 eV/atom) nanocrystals exhibit the onset of self sintering upon impact. At high number densities, adherent, conductive lines are formed from deposited silver nanocrystals. Line widths of 33 micrometers FWHM are directly written onto substrates using a 200 micrometers diameter nozzle.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 2001
- Accession Number
- ADP012203
Entities
People
- D. T. O'brien
- G. Malyavanatham
- J. W. Keto
- M. F. Becker
- W. T. Nichols
Organizations
- University of Texas at Austin