Silica aerogels were patterned with CdS using a photolithographic technique based on local heating with infrared (IR) light. The solvent of silica hydrogels was exchanged with an aqueous solution of the precursors CdNO3 and NH4 OH, all precooled to a temperature of 5°C. Half of the bathing solution was then replaced by a thiourea solution. After thiourea diffused into the hydrogels, the samples were exposed to a focused IR beam from a continuous wave, Nd-YAG laser. The precursors reacted in the spots heated by the IR beam to form CdS nanoparticles. We lithographed features with a diameter of about 40 µm, which extended inside the monoliths for up to 4 mm. Samples were characterized with transmission electron microscopy and optical absorption, photoluminescence, and Raman spectroscopies. Spots illuminated by the IR beam were made up by CdS nanoparticles dispersed in a silica matrix. The CdS nanoparticles had a diameter in the 4-6 nm range in samples exposed for 4 min to the IR beam, and of up to 100 nm in samples exposed for 10 min.
M. F. Bertino et al., "Laser Writing of Semiconductor Nanoparticles and Quantum Dots," Applied Physics Letters, vol. 85, no. 24, pp. 6007-6009, American Institute of Physics (AIP), Jan 2004.
The definitive version is available at http://dx.doi.org/10.1063/1.1836000
Mining and Nuclear Engineering
Keywords and Phrases
Compounds; Nanolithography; Photolithography; Semiconductor Quantum Dots; Transmission Electron Microscopy
Article - Journal
© 2004 American Institute of Physics (AIP), All rights reserved.