1200dpi thin film LED array by silicon photonics technology

Abstract

Higher density single crystal thin film light emitting diode (LED) arrays have been studied. Bonding of epitaxial thin film (epifilm) LEDs of about 2 mum in thickness has been achieved on CMOS IC drivers and other dissimilar material substrates by intermolecular force ("Epi Film Bonding (EFB)" technology). The epifilm LED array provides good enough characteristics to apply in LED printheads (small variation of emitted light power (< plusmn 5%) and long lifetime (>1000 h)). Fabrication test of two dimensional (2D) epifilm LED arrays shows that 2D 1200 dpi epifilm LED arrays (a small light emitting region of 10 mum times 10 mum and a fine array pitch of 21.2 mum) achieves good performance to display characters. Bonding of 1200 dpi epifilm LED arrays on diamond-like carbon (DLC) thin films having high thermal conductivity has been tested for the first time. The test result shows that good bonding of small epifilms (10 mum times 10 mum) on the DLC thin film can be achieved. The LED array that is bonded on the DLC thin film formed on the Si substrate shows higher thermal conduction character; rough estimation of LED temperature suggests about 50 degrees centigrade even at a very high LED current density of 20 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .