Author : Robert Stevens
Publisher :
Page : pages
File Size : 28,79 MB
Release : 1994
Category :
ISBN :
The design of an electroluminescent device is presented which facilitates the manufacture of 600 dpi electrophotographic image bar arrays. Matrix addressed laterally emitting alternating current thin film electroluminescent devices, LETFELs, provide intense light sources. Electroluminescent materials are deposited on pre-fabricated 4" Si substrates by RF magnetron sputtering from ZnS:Mn and ZnS:S powder and Y2O3 sintered targets. Silicon thin film technology is utilised to pattern A1 and poly-Si conducting networks which address a linear arrays of LETFEL devices. Micro-fabrication of LETFEL materials by Ar ion sputtering and wet-chemical etching produce via holes for metallisation and light emitting facets. Automated dicing of fabricated wafers define the LETFEL die. Pick-and-place techniques butt die end-to-end to produce a linear array. Implementation of a 6 to 1 level of matrix addressing for the preferred LETFEL die, ensures optimisation of cost, excitation frequency, lateral brightness, manufacturability, yield and the use of presently available drive electronics and assembly processes. High voltage bipolarity pulses combined with low voltage pulse positioning control the LETFEL array. Worst case electrical analysis suggests pulse widths of 5us, which can be configured to 8.3kHz excitation frequency. This corresponds to a forward brightness of 53,000fL for a conventional LETFEL structure and is insufficient for 8ppm printing. A novel barrier layer structure incorporated into fabricated wafers has brightnesses which exceeds the requirement for 8 ppm, when driven at lower excitation frequencies. An efficient out-coupling process has been identified for miniature displays. Presently micro-mirrors fabricated from SiO2 reflect the direct lateral emission through 90 degrees.....