Lighting in the knowledge LED epitaxial growth technology is introduced
Release Date：[2015/8/6 17:27:31] Total read [836] Times
Extended piece of technology and equipment is the key to the epitaxial wafer manufacturing technology, Metal organic chemical vapor deposition (Metal - OrganicChemicalVaporDeposition, MOCVD) technology growth groups III and V, II - VI compounds and the main method of thin layer of single crystal alloy. Here with all of you to introduce the light LED epitaxial growth technology of the relevant information in knowledge stage lighting equipment.
(1), hydride vapor phase epitaxy (HVPE) technology
Using this technique can quickly grow low bit error density thick film, can be used for using other methods to homogeneous epitaxial growth substrate. And substrate separation of GaN film could be substitute for single crystal GaN chip. HVPE drawback is that it is difficult to precise control of film thickness, the reaction gas is corrosive to equipment, and effect for improving the purity of GaN material.
(2), research and development of shorter wavelength UVLED epitaxial wafer materials
It for the development of UV trichromatic fluorescent white light LED to lay the solid foundation. A lot of efficient fluorescent powder for UV light excitation, the luminous efficiency than the current use of YAG: Ce system high many, so easy to make white LED up to a new level.
(3), improvement of two-step process
The current commercial production USES a two step process, but a number of substrate, that has limited, 6 machine more mature, about 20 pieces of the machine is still in mature, after a few more uniformity result in epitaxial wafer is not enough. Trend is two directions: one is to develop can be packed in a reaction chamber to more substrate epitaxial growth, more suitable for large-scale production technology, to reduce costs; Another direction is highly automated repeatability of single piece of equipment.
(4), the development "photons then loops" technology
Japan's Sumitomo in January 1999, developed the ZnSe material of white LED. Its technology is first in ZnSe growth of single crystal substrate layer CdZnSe film, after electrify blue light from the film and the substrate ZnSe function complementary yellow light, forming a white light source. The Boston university photonics research center in the same way on the blue light GaN - LED stacked layer AlInGaP semiconductor compound, also generate white light.
(5), dangling epitaxial wafer technology (Pendeo - epitaxy)
In this way can greatly reduce the lattice mismatch between substrate and epitaxial layer and thermal mismatch caused by a large number of lattice defects in epitaxial wafer layer, thus further improve the quality of the GaN epitaxial layers of crystals. In the appropriate substrate (6 h - SiC or Si) using two-step process grow GaN epitaxial layers. And then to district etching of epitaxial wafer membrane, has been into the substrate. Thus formed the GaN buffer layer/substrate of the columnar structure and the shape of the groove alternating. Then GaN epitaxial layers of growth, the growth of GaN epitaxial layers above dangling in the groove, the original GaN epitaxial layer wall of lateral epitaxial growth. In this way, don't need a mask, so to avoid the contact between GaN and pickled membrane materials.
6, selective epitaxy growth or lateral epitaxial growth technology
Using this technology can further reduce bit fault density, improving the quality of GaN epitaxial layers of crystals. In the appropriate substrate deposits a layer of GaN (sapphire or silicon carbide), and deposits a layer of more on its crystalline state of the SiO mask layer, then use photolithography and etching technology, formation of GaN in the Windows and the mask layer. Later in the growth process, the epitaxial wafer GaN growth on GaN Windows first, and then lateral growth in the SiO bar.
All landowners, developing multiple quantum well type chip technology
Multiple quantum well type is in the process of chip light-emitting layer growth, doped with different impurities to make different quantum well structure, through different quantum well from a variety of photon compound directly emit white light. The method to improve the luminous efficiency, can reduce cost, reduce the difficulty of the packaging and the control of the circuit, But the technology difficulty is relatively large.
(1), hydride vapor phase epitaxy (HVPE) technology
Using this technique can quickly grow low bit error density thick film, can be used for using other methods to homogeneous epitaxial growth substrate. And substrate separation of GaN film could be substitute for single crystal GaN chip. HVPE drawback is that it is difficult to precise control of film thickness, the reaction gas is corrosive to equipment, and effect for improving the purity of GaN material.
(2), research and development of shorter wavelength UVLED epitaxial wafer materials
It for the development of UV trichromatic fluorescent white light LED to lay the solid foundation. A lot of efficient fluorescent powder for UV light excitation, the luminous efficiency than the current use of YAG: Ce system high many, so easy to make white LED up to a new level.
(3), improvement of two-step process
The current commercial production USES a two step process, but a number of substrate, that has limited, 6 machine more mature, about 20 pieces of the machine is still in mature, after a few more uniformity result in epitaxial wafer is not enough. Trend is two directions: one is to develop can be packed in a reaction chamber to more substrate epitaxial growth, more suitable for large-scale production technology, to reduce costs; Another direction is highly automated repeatability of single piece of equipment.
(4), the development "photons then loops" technology
Japan's Sumitomo in January 1999, developed the ZnSe material of white LED. Its technology is first in ZnSe growth of single crystal substrate layer CdZnSe film, after electrify blue light from the film and the substrate ZnSe function complementary yellow light, forming a white light source. The Boston university photonics research center in the same way on the blue light GaN - LED stacked layer AlInGaP semiconductor compound, also generate white light.
(5), dangling epitaxial wafer technology (Pendeo - epitaxy)
In this way can greatly reduce the lattice mismatch between substrate and epitaxial layer and thermal mismatch caused by a large number of lattice defects in epitaxial wafer layer, thus further improve the quality of the GaN epitaxial layers of crystals. In the appropriate substrate (6 h - SiC or Si) using two-step process grow GaN epitaxial layers. And then to district etching of epitaxial wafer membrane, has been into the substrate. Thus formed the GaN buffer layer/substrate of the columnar structure and the shape of the groove alternating. Then GaN epitaxial layers of growth, the growth of GaN epitaxial layers above dangling in the groove, the original GaN epitaxial layer wall of lateral epitaxial growth. In this way, don't need a mask, so to avoid the contact between GaN and pickled membrane materials.
6, selective epitaxy growth or lateral epitaxial growth technology
Using this technology can further reduce bit fault density, improving the quality of GaN epitaxial layers of crystals. In the appropriate substrate deposits a layer of GaN (sapphire or silicon carbide), and deposits a layer of more on its crystalline state of the SiO mask layer, then use photolithography and etching technology, formation of GaN in the Windows and the mask layer. Later in the growth process, the epitaxial wafer GaN growth on GaN Windows first, and then lateral growth in the SiO bar.
All landowners, developing multiple quantum well type chip technology
Multiple quantum well type is in the process of chip light-emitting layer growth, doped with different impurities to make different quantum well structure, through different quantum well from a variety of photon compound directly emit white light. The method to improve the luminous efficiency, can reduce cost, reduce the difficulty of the packaging and the control of the circuit, But the technology difficulty is relatively large.