Fraunhofer researchers have discovered silicon structures filled with phosphor as an alternative to LED matrix systems. These structures are said to offer a higher spatial resolution and a better contrast ratio.
Laser scanning microscopy image of a single pixel.
Fraunhofer AWZ Soest
White LED matrix systems are currently state of the art. In collaboration with Fraunhofer ISIT, researchers at the Fraunhofer Application Center for Inorganic Phosphors in Soest, Germany, have developed silicon structures filled with phosphors which, in addition to high resolution, also enable active air or water cooling of the phosphor. The required structures are etched onto a silicon wafer and then filled with a fluorescent powder. "These pixelated phosphors make far higher spatial resolution possible since pixelated microstructures with dimensions of a few micrometres can be generated," explains Dr. Franziska Steudel, Team Leader "Phosphor Design" at the Fraunhofer Application Center (AWZ, Anwendungszentrum) in Soest.
The structures therefore offer a very high contrast resolution and Lambertian reflectance if they are stimulated by a blue laser beam. The surrounding silicon walls improve the optical resolution due to their thermal conductivity and can dissipate heat efficiently. Due to the porosity of the phosphor layer, phosphor in applications with very high power density can also be actively cooled with air or water. The research results were published in the journal "elektronik industrie".