NSF Award
9632164
*** 9632164 Vernon This Phase I STTR project will develop thin film electroluminescent displays on plastic substrates. The zinc gallate (ZnGa204) phosphor host will be grown by metalorganic chemical vapor deposition (MOCVD) at ~425 C on a high-temperature Kapton substrate. Luminescent centers will be introduced by ion implantation, and a pulsedlaser anneal of the phosphor without damaging the substrate. Phase I will demonstrate that oxide phosphors can be deposited by MOCVD at temperatures compatible with Kapton, a plastic usable up to ~450 C. Because Kapton, and other polyimide materials, are not optically clear, structures having light emission from the top (nonsubstrate) side will be developed. Substrate temperature will be controlled by water cooling during ion implantation of luminescence centers. Dopant activation and crystal enhancement will be by pulsed ultraviolet (UV) laser annealing, so as not to degrade the plastic substrate. Development of the proper UV anneal, using an excimer laser, will be conducted at the University of Florida. Glass substrates will be included as experimental controls. Spire will compare the quality of MOCVD-grown ZnGa204 films on plastic and glass substrates by x-ray diffraction and electron microscopy, and photoluminescence and cathodoluminescence tests will be performed on annealed ZnGa2O4 films. The University of Florida will then fabricate and test electroluminescent devices on both glass and plastic substrates. Phase II will include optimization of phosphor growth, luminescence-center implantation, and laser annealing on plastic substrates. Low-temperature MOCVD of high-dielectric ceramic films will be developed to achieve lower voltage operation and higher luminescent efficiency. Spire's MOCVD oxide reactor is set up to deposit phosphor as well as high-dielectric materials, and Spire will also attempt to improve electroluminescent efficiency and lower fabrication costs by rapid deposition of multilayer dielectric-phosphor-dielectric stacks in the same reactor. This research will result in the capability to fabricate flat-panel EL displays on plastic substrates for rugged, bright, lightweight, handheld information terminals to provide better graphical communication to personnel in demanding environments. ***
