Regensburg 2002 – wissenschaftliches Programm
HL 38.44: Poster
Donnerstag, 14. März 2002, 16:30–19:00, Poster A
EPR investigation on ZnO nanocrystals — •Huijuan Zhou1, A. Hofstaetter1, D. M. Hofmann1, B. K. Meyer1, and A. Rodina2 — 1I. Physikalisches Institut, Justus-Liebig-Universitaet Giessen — 2Ioffe Institut, St. Petersburg, Russland
ZnO nanocrystals with diameters ranging from 3 nm to 50 nm were prepared via a wet chemical method and post-growth annealing treatments. The electron paramagnetic resonance spectra of the nanocrystals with large diameters show the resonance of electron centers with a g-value close to the shallow donors in bulk ZnO. The temperature dependence of the resonance, which can be measured in the nanocrystals up to room temperature, shows the behavior expected from k*p theory for shallow donors, i.e. it decreases with increasing temperature due to the shrinkage of the bandgap. Reducing the nanocrystal size the g-value tends towards g = 2.00 in agreement with recent theoretical predictions. However, form a detailed study of the saturation behaviour of the resonance we got evidence that it consists of two superimposed signals which we tentatively attribute to centers located in the core of the nanocrystals and centers located near the surface.