In this paper, a new equivalent circuit model of GaN-based light emitting diodes （LEDs） is established. The impact of the series resistance to luminous efficacy is simulated using the MATLAB software. GaN-based LEDs...In this paper, a new equivalent circuit model of GaN-based light emitting diodes （LEDs） is established. The impact of the series resistance to luminous efficacy is simulated using the MATLAB software. GaN-based LEDs with different n- contact electrode materials （LEDs with Ni/Au and LEDs with Cr/Au） are fabricated. By comparing and analyzing the results of performances, we concluded that both the series resistance and the carrier loss could affect the luminous efficacy severely. LEDs with lower series resistance have higher luminous efficacy and its efficiency droop is alleviated simultaneously. To improve luminous efficacy, the fabrication process should be optimized for lower series resistance.展开更多
Progress with GaN-based light emitting diodes （LEDs） that incorporate nanostructures is reviewed, especially the re- cent achievements in our research group. Nano-patterned sapphire substrates have been used to grow...Progress with GaN-based light emitting diodes （LEDs） that incorporate nanostructures is reviewed, especially the re- cent achievements in our research group. Nano-patterned sapphire substrates have been used to grow an A1N template layer for deep-ultraviolet （DUV） LEDs. One efficient surface nano-texturing technology, hemisphere-cones-hybrid nanostruc- tures, was employed to enhance the extraction efficiency of InGaN flip-chip LEDs. Hexagonal nanopyramid GaN-based LEDs have been fabricated and show electrically driven color modification and phosphor-free white light emission because of the linearly increased quantum well width and indium incorporation from the shell to the core. Based on the nanostruc- tures, we have also fabricated surface plasmon-enhanced nanoporous GaN-based green LEDs using AAO membrane as a mask. Benefitting from the strong lateral SP coupling as well as good electrical protection by a passivation layer, the EL intensity of an SP-enhanced nanoporous LED was significantly enhanced by 380%. Furthermore, nanostructures have been used for the growth of GaN LEDs on amorphous substrates, the fabrication of stretchable LEDs, and for increasing the 3-dB modulation bandwidth for visible light communication.展开更多
InGaN-based light-emitting diodes with p-GaN and p-A1GaN hole injection layers are numerically studied using the APSYS simulation software. The simulation results indicate that light-emitting diodes with p-A1GaN hole ...InGaN-based light-emitting diodes with p-GaN and p-A1GaN hole injection layers are numerically studied using the APSYS simulation software. The simulation results indicate that light-emitting diodes with p-A1GaN hole injection layers show superior optical and electrical performance, such as an increase in light output power, a reduction in current leakage and alleviation of efficiency droop. These improvements can be attributed to the p-A1GaN serving as hole injection layers, which can alleviate the band bending induced by the polarization field, thereby improving both the hole injection efficiency and the electron blocking efficiency.展开更多
GaN-based light-emitting diodes （LEDs） with surface-textured indium tin oxide （ITO） as a transparent current spreading layer were fabricated. The ITO surface was textured by inductively coupled plasma （ICP） etch...GaN-based light-emitting diodes （LEDs） with surface-textured indium tin oxide （ITO） as a transparent current spreading layer were fabricated. The ITO surface was textured by inductively coupled plasma （ICP） etching technology using a monolayer of nickel （Ni） nanoparticles as the etching mask. The luminance intensity of ITO surface-textured GaN-based LEDs was enhanced by about 34% compared to that of conventional LED without textured ITO layer. In addition, the fabricated ITO surface-textured GaN-based LEDs would present a quite good performance in electrical characteristics. The results indicate that the scattering of photons emitted in the active layer was greatly enhanced via the textured ITO surface, and the ITO surface-textured technique could have a potential application in improving photoelectric characteristics for manufacturing GaN-based LEDs of higher brightness.展开更多
InGaN based light-emitting diodes （LEDs） with dip-shaped quantum wells and conventional rectangular quantum ~lls are numerically investigated by using the APSYS simulation software. It is found that the structure wi...InGaN based light-emitting diodes （LEDs） with dip-shaped quantum wells and conventional rectangular quantum ~lls are numerically investigated by using the APSYS simulation software. It is found that the structure with dip- aped quantum wells shows improved light output power, lower current leakage and less efficiency droop. Based on Lmerical simulation and analysis, these improvements on the electrical and the optical characteristics are attributed ainly to the alleviation of the electrostatic field in dip-shaped InGaN/GaN multiple quantum wells （MQWs）.展开更多
InGaN based light-emitting diodes （LEDs） with different electron blocking layers have been numerically investi- gated using the APSYS simulation software. It is found that the structure with a p-AlInN electron block...InGaN based light-emitting diodes （LEDs） with different electron blocking layers have been numerically investi- gated using the APSYS simulation software. It is found that the structure with a p-AlInN electron blocking layer showes improved light output power, lower current leakage, and smaller efficiency droop. Based on numerical simulation and analysis, these improvements of the electrical and optical characteristics are mainly attributed to the efficient electron blocking in the InGaN/GaN multiple quantum wells （MQWs）.展开更多
GaN/InGaN superlattice barriers are used in InGaN-based light-emitting diodes （LEDs）. The electrostatic field in the quantum wells, electron hole wavefunction overlap, carrier concentration, spontaneous emission spe...GaN/InGaN superlattice barriers are used in InGaN-based light-emitting diodes （LEDs）. The electrostatic field in the quantum wells, electron hole wavefunction overlap, carrier concentration, spontaneous emission spectrum, light-current performance curve, and internal quantum efficiency are numerically investigated using the APSYS simulation software. It is found that the structure with GaN/InGaN superlattice barriers shows improved light output power, and lower current leakage and efficiency droop. According to our numerical simulation and analysis, these improvements in the electrical and optical characteristics are mainly attributed to the alleviation of the electrostatic field in the active region.展开更多
The advantages of a blue InGaN-based light-emitting diode with a p-InGaN layer inserted in the GaN barriers is studied. The carrier concentration in the quantum well, radiative recombination rate in the active region,...The advantages of a blue InGaN-based light-emitting diode with a p-InGaN layer inserted in the GaN barriers is studied. The carrier concentration in the quantum well, radiative recombination rate in the active region, output power, and internal quantum efficiency are investigated. The simulation results show that the InGaN-based light-emitting diode with a p-InGaN layer inserted in the barriers has better performance over its conventional counterpart and the light emitting diode with p-GaN inserted in the barriers. The improvement is due to enhanced Mg acceptor activation and enhanced hole injection into the quantum wells.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11204009)
文摘In this paper, a new equivalent circuit model of GaN-based light emitting diodes （LEDs） is established. The impact of the series resistance to luminous efficacy is simulated using the MATLAB software. GaN-based LEDs with different n- contact electrode materials （LEDs with Ni/Au and LEDs with Cr/Au） are fabricated. By comparing and analyzing the results of performances, we concluded that both the series resistance and the carrier loss could affect the luminous efficacy severely. LEDs with lower series resistance have higher luminous efficacy and its efficiency droop is alleviated simultaneously. To improve luminous efficacy, the fabrication process should be optimized for lower series resistance.
基金Project supported by the National Natural Science Foundation of China(Grant No.61334009)the National High Technology Research and Development Program of China(Grant Nos.2015AA03A101 and 2014BAK02B08)+1 种基金China International Science and Technology Cooperation Program(Grant No.2014DFG62280)the"Import Outstanding Technical Talent Plan"and"Youth Innovation Promotion Association Program"of the Chinese Academy of Sciences
文摘Progress with GaN-based light emitting diodes （LEDs） that incorporate nanostructures is reviewed, especially the re- cent achievements in our research group. Nano-patterned sapphire substrates have been used to grow an A1N template layer for deep-ultraviolet （DUV） LEDs. One efficient surface nano-texturing technology, hemisphere-cones-hybrid nanostruc- tures, was employed to enhance the extraction efficiency of InGaN flip-chip LEDs. Hexagonal nanopyramid GaN-based LEDs have been fabricated and show electrically driven color modification and phosphor-free white light emission because of the linearly increased quantum well width and indium incorporation from the shell to the core. Based on the nanostruc- tures, we have also fabricated surface plasmon-enhanced nanoporous GaN-based green LEDs using AAO membrane as a mask. Benefitting from the strong lateral SP coupling as well as good electrical protection by a passivation layer, the EL intensity of an SP-enhanced nanoporous LED was significantly enhanced by 380%. Furthermore, nanostructures have been used for the growth of GaN LEDs on amorphous substrates, the fabrication of stretchable LEDs, and for increasing the 3-dB modulation bandwidth for visible light communication.
基金Supported by Foundations of Pujiang Talented Person Plans(No.05PJ14037)Nanotechnology of Shanghai Municipal Science & Technology Committee(No.0552nm042)Shanghai-Applied Materials Research and Development fund(No.0519)
基金Project supported by the National Natural Science Foundation of China (Grant No. 50602018)the Science and Technology Program of Guangdong Province,China (Grant Nos. 2010B090400456,2009B011100003,and 2010A081002002)the Science and Technology Program of Guangzhou City,China (Grant No. 2010U1-D00191)
文摘InGaN-based light-emitting diodes with p-GaN and p-A1GaN hole injection layers are numerically studied using the APSYS simulation software. The simulation results indicate that light-emitting diodes with p-A1GaN hole injection layers show superior optical and electrical performance, such as an increase in light output power, a reduction in current leakage and alleviation of efficiency droop. These improvements can be attributed to the p-A1GaN serving as hole injection layers, which can alleviate the band bending induced by the polarization field, thereby improving both the hole injection efficiency and the electron blocking efficiency.
基金Project supported by the Production and Research Program of Guangdong Province and Ministry of Education (Grant No.2009B090300338)Guangdong Natural Science Foundation of China (Grant No.8251063101000007)+1 种基金Guangdong Science and Technology Plan of China (Grant No.2008B010200004)the Student Research Project of South China Normal University (Grant No.09XXKC03)
文摘GaN-based light-emitting diodes （LEDs） with surface-textured indium tin oxide （ITO） as a transparent current spreading layer were fabricated. The ITO surface was textured by inductively coupled plasma （ICP） etching technology using a monolayer of nickel （Ni） nanoparticles as the etching mask. The luminance intensity of ITO surface-textured GaN-based LEDs was enhanced by about 34% compared to that of conventional LED without textured ITO layer. In addition, the fabricated ITO surface-textured GaN-based LEDs would present a quite good performance in electrical characteristics. The results indicate that the scattering of photons emitted in the active layer was greatly enhanced via the textured ITO surface, and the ITO surface-textured technique could have a potential application in improving photoelectric characteristics for manufacturing GaN-based LEDs of higher brightness.
基金supported by the National Natural Science Foundation of China (Grant No. 50602018)the Science and Technology Program of Guangdong Province of China (Grant Nos. 2010B090400456, 2009B011100003, and 2010A081002002)the Scienceand Technology Program of Guangzhou City, China (Grant No. 2010U1-D00191)
文摘InGaN based light-emitting diodes （LEDs） with dip-shaped quantum wells and conventional rectangular quantum ~lls are numerically investigated by using the APSYS simulation software. It is found that the structure with dip- aped quantum wells shows improved light output power, lower current leakage and less efficiency droop. Based on Lmerical simulation and analysis, these improvements on the electrical and the optical characteristics are attributed ainly to the alleviation of the electrostatic field in dip-shaped InGaN/GaN multiple quantum wells （MQWs）.
基金Project supported by the National Natural Science Foundation of China (Grant No.50602018)the Science and Technology Program of Guangdong Province,China (Grant Nos.2010B090400456,2009B011100003,and 2010A081002002)the Science and Technology Program of Guangzhou City,China (Grant No.2010U1-D00191)
文摘InGaN based light-emitting diodes （LEDs） with different electron blocking layers have been numerically investi- gated using the APSYS simulation software. It is found that the structure with a p-AlInN electron blocking layer showes improved light output power, lower current leakage, and smaller efficiency droop. Based on numerical simulation and analysis, these improvements of the electrical and optical characteristics are mainly attributed to the efficient electron blocking in the InGaN/GaN multiple quantum wells （MQWs）.
基金supported by the National Natural Science Foundation of China (Grant No. 51172079)the Science and Technology Program of Guangdong Province,China (Grant Nos. 2010B090400456 and 2010A081002002)the Science and Technology Program of Guangzhou City, China (Grant No. 2011J4300018)
文摘GaN/InGaN superlattice barriers are used in InGaN-based light-emitting diodes （LEDs）. The electrostatic field in the quantum wells, electron hole wavefunction overlap, carrier concentration, spontaneous emission spectrum, light-current performance curve, and internal quantum efficiency are numerically investigated using the APSYS simulation software. It is found that the structure with GaN/InGaN superlattice barriers shows improved light output power, and lower current leakage and efficiency droop. According to our numerical simulation and analysis, these improvements in the electrical and optical characteristics are mainly attributed to the alleviation of the electrostatic field in the active region.
文摘The advantages of a blue InGaN-based light-emitting diode with a p-InGaN layer inserted in the GaN barriers is studied. The carrier concentration in the quantum well, radiative recombination rate in the active region, output power, and internal quantum efficiency are investigated. The simulation results show that the InGaN-based light-emitting diode with a p-InGaN layer inserted in the barriers has better performance over its conventional counterpart and the light emitting diode with p-GaN inserted in the barriers. The improvement is due to enhanced Mg acceptor activation and enhanced hole injection into the quantum wells.
