Tailoring of nanocrystal sizes in CdSe films prepared by chemical deposition

We report on the control of nanocrystal sizes in nanocrystalline films of CdSe prepared by chemical solution deposition. We studied the effect of growth duration, of the light illumination during the growth, and of subsequent heat treatment of the films. Nanocrystals with radii from 1.9 to 10 nm were prepared and characterized by transmission electron microscopy, X-ray diffraction, and optical photoluminescence and absorption spectroscopy. We have observed the cubic and hexagonal structure for small and large nanocrystals, respectively. We interpret the trap-related photoluminescence in nanocrystals in terms of recombination of a deeply trapped hole with an electron in an interior slate or in a shallow trap. (C) 2000 Elsevier Science B.V. All rights reserved.