| The successful development of GaN-based LED on silicon substrate overwrites the history of InGaN LEDs only grown on sapphire and Silicon carbon, which has the more potential for industry technical route and it had attracted many relevant researches coming from dozens of research units and companies in the world. Recently, several units have reported their new research results on LEDs on Si substrate, but there has been apart from the results of LEDs on sapphire and SiC substrates, which mainly reflects in the lumen efficiency and industrialization technologies. The stress of GaN grown on Si is different from the stress of grown on sapphire and SiC, leading to the discrepancy of polarization in the materials, especially affect the properties correlated with growth and polarity, which is crucial for the lumen efficiency of LED. Up to the present, some important physical issue about the light emitting essence has not been clear. In addition, different substrate materials induce the discrepancy of chip process. The physical and chemical characters among silicon, sapphire and SiC are widely different, this result in that the chip process of LEDs on sapphire is not adapt to LEDs on Silicon. Therefore, the development of an advanced chip manufacturing technology of LED on silicon is equally important.From the research into relevant characteristics of the quantum well and chip technology, we change the growth process and structural design of quantum well, then by photoluminescence (PL), electroluminescence (EL), fluorescence (FL) and other means, we analysis the luminescence properties of quantum wells. Otherwise, we improve p-type contact of the chip and optimize the process of p-surface passivation, explore a thin film LED chip technology by electroplating a metal substrate to replace original silicon substrate. Based on the above aspects, we find the following important results:Through discussion of variable temperature EL features of a monochrome single quantum well and monochrome multi-quantum-well green LEDs on Si, we find that compared with the monochrome multi-quantum well, monochrome luminous efficiency. In addition, Si-doping of barrier can make FL picture uniform significantly. However, the closer of the position between the Si-doped barrier and the injection layer, the lower of the reverse voltage, the worse of ESD performance. Contrast samples of injection layer doped silicon or not, experimental results reflect consistently that the doped silicon before the well increases the compressive stress in well.Different thick. Ni layers were deposited on the GaN-based LED films grown on Si(111) substrate, then LED films are annealed at400℃～750℃in the Atmosphere of N2:O2=4:1. The Pt/p-GaN contact layer is prepared after removing the Ni-capping layer. It is found that, annealing temperature and thickness of Ni-capping layer each have an important influence on the p-type contacts of GaN-based LED films. The Ni film can significantly reduce the activation temperature of Mg acceptor of the p-type GaN. The characteristic of p-type contact of Ni-capping sample becomes better first then turns worse with the annealing temperature and it becomes better then turns worse and then better with Ni-capping thickness. After optimization, the specific contact resistivity of Pt/p-GaN in the case of no second annealing can be reach6.1×10-5Ω·cm2, when Ni-assisted layer thickness is1.5nm and its annealing temperature is450℃.The effects of Ni-assisted annealing on the surface morphologies of GaN-based LED films on Si substrate were studied. A wet etching method using acid-hydrogen peroxide was adopted to boil films surface after activation. We found that some nano-pits appeared on surfaces while original surface step structure was still clearly visible, which shows a defect-selective etching characteristic. Otherwise, we demonstrate the surface morphology can be affected by Ni-assisted annealing. We explain the forming reason of the pits maybe related to dislocation outcrops and polarity inversion of p-GaN which caused by heavily doped and V-pits in quantum wells. The formation and growth of corrosion pits after acid-hydrogen peroxide etched was promoted by Ni-capping annealing.Discussing the feasibility of metal or insulating material as the material of p-surface passivation. Cr is used as the n-type contact usually, of which the purpose of p-surface passivation can be achieved under the conditions of the silver alloy. Finally, combined with silicon-based TF-chip technology, if be able to choose a non-conductive insulating material as a p-surface passivation material, and its feasibility is if the LED chip process does not exist large stress, the use of silicon nitride, silicon oxide or PI as a p-surface passivation material is feasible.GaN LED films grown on Si (111) substrate were transfer onto copper, chromium, and copper, nickel metal substrates by electroplating separately. In chip processing, LED film is by tensile stress into compressive stress, then compressive stress continuously released. The study had found that CuNi substrate had the better heat dispersion property than CuCr substrate. The high resolution XRD show that the residual tensile stress exists in the LED film on CuCr substrate and the compressive stress exist in the LED film on CuNi substrate. CuNi LED had the stable electrical performance after aging192h under the condition of room temperature,900mA. The reliability of electroplated CuNi substrate LED had reached the demands of commercialization.Above results have been used in the research on related National High Technology Research and Development Program863of our institute and in related industrialization. Good effects have been achieved.
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