STRUCTURES AND OPTICAL-PROPERTIES OF ORGANIC-INORGANIC SUPERLATTICES

A new class of superlattice materials consisting of alternating layers of organic and inorganic materials has been prepared from 8-hydroxyquinoline aluminum (Alq) and MgF2 by vacuum deposition. The Alq layer thickness in the superlattices was varied from 10 to 50 angstrom. Small-angle x-ray diffraction measurements indicate that the superlattices have very uniform layered structure throughout the entire stack, and the interfacial roughness is much smaller than 10 angstrom. From the optical absorption and photoluminescence measurements, it is found that the exciton energy shifts to higher energy with decreasing Alq layer thickness. The changes of the exciton energy could be interpreted as the confinement effects of exciton in the Alq thin layers.