Technologies and Devices International公司(TDI)推出一种新产品样品，蓝宝石A1GaN模板。蓝宝石A1GaN材料在紫外线(UV)光谱区为透明，针对高功率基于GaN的UV发光二极管应用，包括工作在波长为250nm或更长应用的深UV发射器。工作在UV和...Technologies and Devices International公司(TDI)推出一种新产品样品，蓝宝石A1GaN模板。蓝宝石A1GaN材料在紫外线(UV)光谱区为透明，针对高功率基于GaN的UV发光二极管应用，包括工作在波长为250nm或更长应用的深UV发射器。工作在UV和深UV光谱区基于GaN的LED用于环境、医疗、生物技术和军事应用。此外，它们还在固态照明应用中有巨大的潜力。展开更多
Blue InGaN light-emitting diodes （LEDs） with a conventional electron blocking layer （EBL）, a common n-A1GaN hole blocking layer （HBL）, and an n-A1GaN HBL with gradual A1 composition are investigated numerically,...Blue InGaN light-emitting diodes （LEDs） with a conventional electron blocking layer （EBL）, a common n-A1GaN hole blocking layer （HBL）, and an n-A1GaN HBL with gradual A1 composition are investigated numerically, which involves analyses of the carrier concentration in the active region, energy band diagram, electrostatic field, and internal quantum efficiency （IQE）. The results indicate that LEDs with an n-AIGaN HBL with gradual AI composition exhibit better hole injection efficiency, lower electron leakage, and a smaller electrostatic field in the active region than LEDs with a conven tional p-A1GaN EBL or a common n-A1GaN HBL. Meanwhile, the efficiency droop is alleviated when an n-A1GaN HBL with gradual A1 composition is used.展开更多
Ni Schottky contacts on A1GaN/CaN heterostructures were fabricated. Some samples were thermally treated in a furnace with N2 ambience at 600 ~C for different times （0.5 h, 4.5 h, 10.5 h, 18 h, 33 h, 48 h, and 72 h）,...Ni Schottky contacts on A1GaN/CaN heterostructures were fabricated. Some samples were thermally treated in a furnace with N2 ambience at 600 ~C for different times （0.5 h, 4.5 h, 10.5 h, 18 h, 33 h, 48 h, and 72 h）, the others were thermally treated for 0.5 h at different temperatures （500 ~C, 600 ~C, 700 ~C, and 800 ~C）. With the measured current-voltage （I-V） and capacitance-voltage （C V） curves and by self-consistently solving Schrodinger＇s and Poisson＇s equations, we found that the relative permittivity of the A1GaN barrier layer was related to the piezoelectric and the spontaneous polarization of the A1GaN barrier layer. The relative permittivity was in proportion to the strain of the A1GaN barrier layer. The relative permittivity and the strain reduced with the increased thermal stress time until the A1GaN barrier totally relaxed （after 18 h at 600 ~C in the current study）, and then the relative permittivity was almost a constant with the increased thermal strcss time. When the sample was treated at 800 ~C for 0.5 h, the relative permittivity was less than the constant due to the huge diffusion of the contact metal atoms. Considering the relation between the relative permittivity of the A1GaN barrier layer and the converse piezoelectric effect, the conclusion can be made that a moderate thermal stress can restrain the converse piezoelectric effect and can improve the stability of A1GaN/GaN heterostructure devices.展开更多
文摘Technologies and Devices International公司(TDI)推出一种新产品样品，蓝宝石A1GaN模板。蓝宝石A1GaN材料在紫外线(UV)光谱区为透明，针对高功率基于GaN的UV发光二极管应用，包括工作在波长为250nm或更长应用的深UV发射器。工作在UV和深UV光谱区基于GaN的LED用于环境、医疗、生物技术和军事应用。此外，它们还在固态照明应用中有巨大的潜力。
基金supported by the National Natural Science Foundation of China(Grant No.61176043)the Special Funds for Provincial Strategic and Emerging Industries Projects of Guangdong Province,China(Grant Nos.2010A081002005,2011A081301003,and 2012A080304016)the Youth Foundation of South China Normal University(Grant No.2012KJ018)
文摘Blue InGaN light-emitting diodes （LEDs） with a conventional electron blocking layer （EBL）, a common n-A1GaN hole blocking layer （HBL）, and an n-A1GaN HBL with gradual A1 composition are investigated numerically, which involves analyses of the carrier concentration in the active region, energy band diagram, electrostatic field, and internal quantum efficiency （IQE）. The results indicate that LEDs with an n-AIGaN HBL with gradual AI composition exhibit better hole injection efficiency, lower electron leakage, and a smaller electrostatic field in the active region than LEDs with a conven tional p-A1GaN EBL or a common n-A1GaN HBL. Meanwhile, the efficiency droop is alleviated when an n-A1GaN HBL with gradual A1 composition is used.
基金Project supported by the National Natural Science Foundation of China (Grant No.10774090)the National Basic Research Program of China (Grant No.2007CB936602)
文摘Ni Schottky contacts on A1GaN/CaN heterostructures were fabricated. Some samples were thermally treated in a furnace with N2 ambience at 600 ~C for different times （0.5 h, 4.5 h, 10.5 h, 18 h, 33 h, 48 h, and 72 h）, the others were thermally treated for 0.5 h at different temperatures （500 ~C, 600 ~C, 700 ~C, and 800 ~C）. With the measured current-voltage （I-V） and capacitance-voltage （C V） curves and by self-consistently solving Schrodinger＇s and Poisson＇s equations, we found that the relative permittivity of the A1GaN barrier layer was related to the piezoelectric and the spontaneous polarization of the A1GaN barrier layer. The relative permittivity was in proportion to the strain of the A1GaN barrier layer. The relative permittivity and the strain reduced with the increased thermal stress time until the A1GaN barrier totally relaxed （after 18 h at 600 ~C in the current study）, and then the relative permittivity was almost a constant with the increased thermal strcss time. When the sample was treated at 800 ~C for 0.5 h, the relative permittivity was less than the constant due to the huge diffusion of the contact metal atoms. Considering the relation between the relative permittivity of the A1GaN barrier layer and the converse piezoelectric effect, the conclusion can be made that a moderate thermal stress can restrain the converse piezoelectric effect and can improve the stability of A1GaN/GaN heterostructure devices.
