After the successful development of group III nitride blue LEDs, the focus of research begallium nitride to shift to the development of group III nitride blue LED devices. Blue LED has broad application prospects in the fields of optical control measurement and high-density optical storage of information. Nichia is currently the world leader in the field of Gallium nitride blue LEDs, and its Gallium nitride blue LEDs have a continuous working life of 10,000 hours at 2mW at room temperature. Using sapphire as the substrate, HP has successfully developed an optical ridge waveguide refractive index guided GaInN/AlGallium nitride multi-quantum well blue LED. CreeResearch is the first company to report on the CWRT blue laser made on SiC.
To the device structure. Following companies such as Nichia, Cree Research and Sony, Fujitsu announced the development of an InGallium nitride blue laser, which can be used in CW at room temperature. Its structure is grown on a SiC substrate and uses a vertical conduction structure (P-type and n-type). Type contacts are fabricated on the top and back sides of the wafer respectively), this is the first report of a CW blue laser with a vertical device structure.
In terms of detectors, a Gallium nitride ultraviolet detector has been developed with a wavelength of 369nm, and its response speed is comparable to that of Si detectors. But research in this area is still in its infancy. Gallium nitride detectors will have important applications in flame detection and missile early warning.
For Gallium nitride materials, the heteroepitaxial defect density is quite high due to the unresolved substrate single crystal for a long time, but the device level is already practical. In 1994, Nichia Chemical made 1200mcd LED, and in 1995 made Zcd blue light (450nm LED) and green light 12cd (520nm LED); in 1998, Japan formulated a 7-year plan for the development of LEDs using wide-bandgap nitride materials. The goal is to develop a high-energy UV LED that is sealed in a fluorescent tube and emits white light by 2005. The power consumption of this white LED is only 1/8 of that of an incandescent lamp and 1/2 of that of a fluorescent lamp. Its lifespan is traditional 50 times to 100 times that of fluorescent lamps. This proves that the development of Gallium nitride materials has been quite successful and has entered the stage of practical application. The formation of InGallium nitride alloys, InGallium nitride/AlGallium nitride dual junction LEDs, In Gallium nitride single quantum well LEDs, and InGallium nitride multiple quantum well LEDs have been successfully developed. InGallium nitrideSQWLED6cd high-brightness pure green tea and 2cd high-brightness blue LEDs have been produced. In the future, it can be combined with AlGaP and AlGaAs red LEDs to form a bright-brightness full-color display. In this way, the white light source mixed with the three primary colors also opens up new application areas, and the era characterized by high reliability and long life LED will come. Both fluorescent lamps and light bulbs will be replaced by LEDs. LED will become the leading product, and Gallium nitride transistors will also develop rapidly with the development of material growth and device technology, becoming a new generation of high-temperature, high-power devices.
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