Optical absorption of indium-island films, consisting of indium particles smaller than about 500Å in diameter, has been investigated experimentally. The interband absorption, the position of which is almost constant (at about 234 nm) irrespective of particle size, was found to disappear in particle sizes below about 200Å in diameter. This disappearance is pointed out to be similar to that in lead particles, where the disappearance is due to the effect of surface atoms. Optical plasma-resonance absorption appeared at 276-335 nm. By simulating this absorption with a Maxwell-Garnett-type effective-medium theory, we investigated the relaxation time τ and the mean free path l of conduction electrons. Τ and l for particle sizes of about 120 and 160Å in diameter are estimated to be (3.33-3.36)×10^<-16> s and 5.79-5.85Å, respectively, which is smaller than the bulk values (0.38×10^<-14> s and 66.1Å). The small τ and l are attributed to the scattering of the conduction electrons at lattice defects internal to the particles.
注記
Copyright 2005 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in E. Anno and M. Tanimoto, Journal of Applied Physics 98(5), 053510 (2005) and may be found at http://link.aip.org/link/?jap/98/053510.
