T. Makino et al., Exciton spectra of ZnO epitaxial layers on lattice-matched substrates grown with laser-molecular-beam epitaxy, APPL PHYS L, 76(24), 2000, pp. 3549-3551
Optical properties in undoped-ZnO epilayers grown by the laser-molecular-be
am epitaxy method on lattice-matched ScAlMgO4 substrates were investigated.
The absorption spectrum at 5 K has two sharp peaks, both of which are attr
ibuted to resonances of A and B excitons, which reflect a small nonradiativ
e damping constant of excitons as well as high film crystallinity accomplis
hed by the virtue of lattice matching. The coupling strengths of exciton-ac
oustic phonon and of exciton-longitudinal-optical phonon were directly dete
rmined from the temperature dependence of exciton absorption spectra indepe
ndently for A and B excitons, which are close in energy and obey the same s
election rule for each other. (C) 2000 American Institute of Physics. [S000
3-6951(00)02924-7].