Optical spectra in ZnO thin films on lattice-matched substrates grown withlaser-MBE method

Optical properties in undoped ZnO thin films grown with laser-molecular bea m epitaxy method on lattice-matched ScAlMgO4 substrates have been investiga ted. The transmission spectrum on this substrate at 6 K has two sharp peaks both of which are attributed to resonances of A- and B-excitons, which ref lects small nonradiative damping constant of excitons as well as high film crystallinity accomplished by virtue of lattice matching. This is, to our b est knowledge, the first observation of exciton absorption and its direct e stimation of parameters related to A- and B-excitons. (C) 2000 Elsevier Sci ence B.V. All rights reserved.