Resolution Microscope LED on the development of strategic emerging industries
Resolution Microscope LED on the development of strategic emerging industries
LED (Light-EmittingDiode, acronym LED) is a light-emitting diode is short, the second half of 2009 , LED market big leap as high-growth emerging industries, is expected to 2015 , LED industry will exceed 500 billion yuan , of which general lighting industry 160 billion yuan , a large -size LCD TV backlight industry 120 billion yuan , 20 billion yuan automotive led down lighting lighting industry , general lighting industry 160 billion yuan , landscape , display and other industry 100 billion yuan.
LED industry chain can be divided into three parts, which are upstream of the growth substrate , wafer manufacturing, midstream and downstream chip packaging applications . In the whole industry chain, the core part of the growth substrate and epitaxial wafer manufacturing sectors , both technical content is relatively high, nearly 70% of total industry output value and profits.
LED current industry trends , the international and domestic markets, “National Semiconductor Lighting Project” under the impetus of China’s LED industry initially formed upstream of the substrate material , including LED, LED epitaxial wafers , led chip preparation , led wall lighting chips, packaging and application of LED products , including a relatively complete industrial chain.
Known semiconductor light-emitting diodes with high conversion efficiency , long life and other advantages, is considered to be the next generation of light sources and will replace the currently used conventional light sources . However, the performance of light-emitting diodes on the current point of view, to achieve this goal , there are many technical difficulties to be overcome , you need to analyze the material characterization , device analysis technology, and increase research efforts. In the light emitting diode device and the chip package structure of the structure , components, and the interface state analytical techniques optical microscopy, scanning electron microscopy , X-ray spectroscopy , secondary ion mass spectrometry equipment and structure of a device failure analysis, led wall light epitaxial process monitoring , improve and enhance the essential analysis tools.
Since sapphire insulation, dielectric loss, high temperature, corrosion . Good thermal conductivity, the mechanical strength is high enough . And can be processed into a flat surface . Transmission band width . It is widely used in industry, national defense , scientific research fields. But also a wide range of uses light-emitting diodes on a good substrate material . In the resulting light-emitting diode is the most promising to become high-brightness light-emitting diodes race sapphire substrate in the next generation of fluorescent light sources are semiconductor light emitting device substrate material . At present these high- brightness light-emitting diodes have been widely used in advertising , traffic lights, instrument lights ; and surgical lights and other fields. With high-brightness light-emitting diode applications increasingly widespread.
LED sapphire (Sapphire) is a single crystal alumina , also known as corundum . Sapphire crystal has excellent optical properties, mechanical properties and chemical stability , high strength, hardness, resistance to erosion, close to 2000 ℃ high temperature in harsh conditions. led wall lamp According to the study suggest that the current can be applied to the LED substrate material only four . As an important technique sapphire crystal , has been in the LED industry to form a more mature fashion and applications .
Polarizing microscope using Zeiss exception can be identified sapphire crystal birefringence . In certain cases, by means of the cone of light microscopy, the crystal can be observed interferogram , determine the crystal axis , used in the direction of observation of each wafer is uniform , in order to determine the quality of the substrate.
LED epitaxial film grown basic principle is: on a substrate heated to a suitable temperature the substrate ( mainly sapphires and , Sic, Si) , the gaseous substance in a controlled InGaAlP delivered to the substrate surface , growing single crystal thin film of a specific . LED epitaxial film growth techniques currently used mainly metal organic chemical vapor deposition (MOCVD)
LED chip, also known as LED light chip is the core component led corn lighting of led lights , but also refers to the PN junction . Its main functions are: electrical energy into light energy , the main material for silicon chips . Semiconductor chip consists of two parts, part of the P -type semiconductor , the hole in it dominates the other side is an N-type semiconductor, here is mainly electronic . But the two semiconductor connected , when between them to form a PN junction . When the current through the wire on the chip when the electron will be pushed to the P region , in the P zone electron hole recombination , and then will be issued in the form of photon energy , which is the principle of LED light. Is the wavelength of the light color of the light , is formed by the PN junction to the materials .
Improve the quality and reduce the epitaxial material lattice defects is to produce high performance and high reliability LED devices premise , or by other means is irreparable .led corn lamp Clear crystal quality of the LED epitaxial material Reliability of the device , through the epitaxial material quality control , to reduce the defect density materials to improve the crystal quality of the epitaxial layer and improve the reliability of the LED devices. Oxidation LED chip thickness: Detection technologies include color comparison, the edge count , interference, ellipsometry , sculptured needle amplitude and scanning electron microscopy.
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