Conference Paper

1200dpi thin film LED array by silicon photonics technology

Oki Digital Imaging Corp., Tokyo
DOI: 10.1109/ECTC.2008.4550060 Conference: Electronic Components and Technology Conference, 2008. ECTC 2008. 58th
Source: IEEE Xplore

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/cm2.

  • [Show abstract] [Hide abstract]
    ABSTRACT: High power white light emitting diodes (LEDs) have begun to play an important role in many illumination applications due to their excellent performance. In this paper, an effective freeform lens design method for extended light source was suggested briefly for the first time and two compact LED packaging freeform lenses, with the material of polycarbonate (PC) and silicone respectively, were designed based on this method. Two novel application-specific LED packages, whose manufacturing processes are compatible with current LED packaging processes, were also presented for street lighting. By comparing with the traditional LED illumination module consisting of an LED and a secondary optical element, the novel application-specific LED package has the advantages of low profile, small volume, high light output efficiency, low cost and convenience for customers to use. Since the application-specific LED packages provide effective solutions to high performance and low cost LED fixtures, they will probably become the trend of LED packages.
    Electronic Components and Technology Conference, 2009. ECTC 2009. 59th; 06/2009
  • [Show abstract] [Hide abstract]
    ABSTRACT: A novel silicon light emitting diode (LED) display array has been fabricated using 0.35 μm standard CMOS technology. In this array, an LED and static random access memory (SRAM) are integrated together in a special layout. The SRAM in each pixel can store the state of the pixel and ensure that the pixel remains lit without persistent flashing. As a result, the control logic is perfectly integrated on the same wafer. Two power sources are used to drive the display array because the LEDs operate at high voltage (supply voltage of 9 V), and the current of the whole display array is about 30–60 mA to display common characters. The display circuit includes digital control logic circuits and SRAM, and requires a supply voltage of 3.3 V. The area of a single pixel is 40×40 μm2, the area of the whole 16×16 LED array is 1 mm2, and the display density is 630 dpi.
    Sciece China. Information Sciences 10/2012; 55(10). · 0.70 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We measured the electron Hall mobility of Si-doped GaAs epitaxial layers (ELs) that were flip-chip-bonded onto an alumina mount to investigate how the quality of the thin layer changes before and after GaAs substrate removal. The electron Hall mobilities at room temperature before and after substrate removal were almost unchanged. Photoluminescence spectra after substrate removal exhibited peak wavelengths at 872-874 nm, which were almost equal to those before substrate removal. This indicates that the quality of ELs was maintained after the process. We measured near-field patterns (NFPs) and far-field patterns (FFPs) of GaAs/AlGaAs vertical-cavity surface-emitting lasers with and without a substrate. There was no change in the full-width-at-half-maximum of the NFP or in the FFP for the optical output range of 0.5-1.3 mW. We confirmed that our novel process is useful for optoelectronic packaging.
    IEEE Transactions on Components, Packaging, and Manufacturing Technology 04/2011; · 1.24 Impact Factor