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-hydroxyqu inoline aluminum (Alq) and MgF2 by vacuum deposition. The Alq layer th ickness in the superlattices was varied from 10 to 50 angstrom. Small- angle x-ray diffraction measurements indicate that the superlattices h ave very uniform layered structure throughout the entire stack, and th e interfacial roughness is much smaller than 10 angstrom. From the opt ical absorption and photoluminescence measurements, it is found that t he exciton energy shifts to higher energy with decreasing Alq layer th ickness. The changes of the exciton energy could be interpreted as the confinement effects of exciton in the Alq thin layers.