We report a new monolithic structure of GaN-based light-emitting diode （LED） which can be operated under high voltage or alternative current. Differing from the conventional single LED chip, the monolithic lightemit...We report a new monolithic structure of GaN-based light-emitting diode （LED） which can be operated under high voltage or alternative current. Differing from the conventional single LED chip, the monolithic lightemitting diode （MLED） array contains microchips which are interconnected in series or parallel. The key chip fabrication processing methods of the monolithic LED array include deep dry etching, sidewall insulated protec- tion, and electrode interconnection. A 12 V GaN-based blue high voltage light emitting diode was designed and fabricated in our experiment. The forward current-voltage characteristics of MLEDs were consistent with those of conventional single junction light emitting diodes.展开更多
Through insertion of an AlGaN/GaN stack between the u-GaN and n-GaN of GaN-based light-emitting diodes （LEDs）, the strain in the epilayer was increased, the dislocation density was reduced. GaN-based LEDs with diffe...Through insertion of an AlGaN/GaN stack between the u-GaN and n-GaN of GaN-based light-emitting diodes （LEDs）, the strain in the epilayer was increased, the dislocation density was reduced. GaN-based LEDs with different Al compositions were compared. 6.8% Al composition in the stacks showed the highest electrostatic discharge （ESD） endurance ability at the human body mode up to 6000 V and the pass yield exceeded 95%.展开更多
Unintentionally doped GaN films grown by MOCVD were irradiated with neutrons at room temperature. In order to investigate the influence of neutron irradiation on the optical properties of GaN films, persistent pho toc...Unintentionally doped GaN films grown by MOCVD were irradiated with neutrons at room temperature. In order to investigate the influence of neutron irradiation on the optical properties of GaN films, persistent pho toconductivity （PPC） and low temperature photoluminescence （PL） measurements were carried out. Pronounced PPC was observed in the samples before and after neutron irradiation without the appearance of a yellow lumi- nescence （YL） band in the PL spectrum, suggesting that the origin of PPC and YL are not related. Moreover, PPC phenomenon was enhanced by neutron irradiation and quenched by the followed annealing process at 900 ℃. The possible origin of PPC is discussed.展开更多
The growth process of three-dimensional growth mode（3D） switching to two-dimensional growth mode （2D） is investigated when GaN films are grown on cone-shaped patterned sapphire substrates by metal-organic chemical...The growth process of three-dimensional growth mode（3D） switching to two-dimensional growth mode （2D） is investigated when GaN films are grown on cone-shaped patterned sapphire substrates by metal-organic chemical vapor deposition.The growth condition of the 3D-2D growth process is optimized to reduce the threading dislocation density（TDD）.It is found that the condition of the 3D layer is critical.The 3D layer keeps growing under the conditions of lowⅤ/Ⅲratio,low temperature,and high pressure until its thickness is comparable to the height of the cone-shaped patterns.Then the 3D layer surrounds the cone-shaped patterns and has inclined side facets and a top（0001） plane.In the following 2D-growth process,inclined side facets coalesce quickly and the interaction of TDs with the side facets causes the TDs to bend over.As a result,the TDD of GaN films can decrease to 1×10~8 cm^（-2）,giving full-width at half maximum values of 211 and 219 arcsec for（002） and（102） omega scans, respectively.展开更多
基金supported by the National High Technology Research and Development of China(Nos.2011AA03A108,2011AA03A105)
文摘We report a new monolithic structure of GaN-based light-emitting diode （LED） which can be operated under high voltage or alternative current. Differing from the conventional single LED chip, the monolithic lightemitting diode （MLED） array contains microchips which are interconnected in series or parallel. The key chip fabrication processing methods of the monolithic LED array include deep dry etching, sidewall insulated protec- tion, and electrode interconnection. A 12 V GaN-based blue high voltage light emitting diode was designed and fabricated in our experiment. The forward current-voltage characteristics of MLEDs were consistent with those of conventional single junction light emitting diodes.
基金supported by the National High Technology Research and Development Program of China(No.2008AA03A197)
文摘Through insertion of an AlGaN/GaN stack between the u-GaN and n-GaN of GaN-based light-emitting diodes （LEDs）, the strain in the epilayer was increased, the dislocation density was reduced. GaN-based LEDs with different Al compositions were compared. 6.8% Al composition in the stacks showed the highest electrostatic discharge （ESD） endurance ability at the human body mode up to 6000 V and the pass yield exceeded 95%.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20111317120005)the Key Program for Science and Technology Research of Higher Education Institution of Hebei Province,China(No.ZD2010124)the National Natural Science Foundation of China(No.61076004)
文摘Unintentionally doped GaN films grown by MOCVD were irradiated with neutrons at room temperature. In order to investigate the influence of neutron irradiation on the optical properties of GaN films, persistent pho toconductivity （PPC） and low temperature photoluminescence （PL） measurements were carried out. Pronounced PPC was observed in the samples before and after neutron irradiation without the appearance of a yellow lumi- nescence （YL） band in the PL spectrum, suggesting that the origin of PPC and YL are not related. Moreover, PPC phenomenon was enhanced by neutron irradiation and quenched by the followed annealing process at 900 ℃. The possible origin of PPC is discussed.
文摘The growth process of three-dimensional growth mode（3D） switching to two-dimensional growth mode （2D） is investigated when GaN films are grown on cone-shaped patterned sapphire substrates by metal-organic chemical vapor deposition.The growth condition of the 3D-2D growth process is optimized to reduce the threading dislocation density（TDD）.It is found that the condition of the 3D layer is critical.The 3D layer keeps growing under the conditions of lowⅤ/Ⅲratio,low temperature,and high pressure until its thickness is comparable to the height of the cone-shaped patterns.Then the 3D layer surrounds the cone-shaped patterns and has inclined side facets and a top（0001） plane.In the following 2D-growth process,inclined side facets coalesce quickly and the interaction of TDs with the side facets causes the TDs to bend over.As a result,the TDD of GaN films can decrease to 1×10~8 cm^（-2）,giving full-width at half maximum values of 211 and 219 arcsec for（002） and（102） omega scans, respectively.
