Strain effects on exciton resonance energies of ZnO epitaxial layers

Magnitudes of strain in ZnO epitaxial layers grown on sapphire(0001) substr ates under various growth conditions were experimentally determined by x-ra y diffraction. We discuss the strain-induced energy shift on the exciton re sonances, the results of which were analyzed theoretically using the Hamilt onian for the valence bands under in-plain biaxial strain. Comparative stud ies with GaN evidenced the advantages of ZnO in terms of sensitivity of the strain-induced energy shift and of piezoelectric effect in heterostructure s. (C) 2001 American Institute of Physics.