The nano-patterned InGaN film was used in green InGaN/GaN multiple quantum wells(MQWs)structure,to relieve the unpleasantly existing mismatch between high indium content InGaN and GaN,as well as to enhance the light o...The nano-patterned InGaN film was used in green InGaN/GaN multiple quantum wells(MQWs)structure,to relieve the unpleasantly existing mismatch between high indium content InGaN and GaN,as well as to enhance the light output.The different self-assembled nano-masks were formed on InGaN by annealing thin Ni layers of different thicknesses.Whereafter,the InGaN films were etched into nano-patterned films.Compared with the green MQWs structure grown on untreated InGaN film,which on nano-patterned InGaN had better luminous performance.Among them the MQWs performed best when 3 nm thick Ni film was used as mask,because that optimally balanced the effects of nano-patterned InGaN on the crystal quality and the light output.展开更多
A homemade 7×2 inch MOCVD system is presented.With this system,high quality GaN epitaxial layers,InGaN/GaN multi-quantum wells and blue LED structural epitaxial layers have been successfully grown. The non-unifor...A homemade 7×2 inch MOCVD system is presented.With this system,high quality GaN epitaxial layers,InGaN/GaN multi-quantum wells and blue LED structural epitaxial layers have been successfully grown. The non-uniformity of undoped GaN epitaxial layers is as low as 2.86%.Using the LED structural epitaxial layers, blue LED chips with area of 350×350μm2 were fabricated.Under 20 mA injection current,the optical output power of the blue LED is 8.62 mW.展开更多
An analysis solution of rate equation is derived for vertical cavity surface-emitting lasers. Based on the enhanced spontaneous emission caused by VCSELs and influence of nonradiative recombination, the relation betwe...An analysis solution of rate equation is derived for vertical cavity surface-emitting lasers. Based on the enhanced spontaneous emission caused by VCSELs and influence of nonradiative recombination, the relation between output properties and structural parameters of multi-quantum wells (MQWs) is obtained. It was found that the characteristic curve of a“thresholdless”laser is strongly nonradiative depopulation-dependent. When the nonradiative depopulation is no zero, the light-current characteristic is not linearly even for an ideal closed microcavity. The light output is increased by the enhanced well number and by the reduced width. In particular, a lower threshold current density for MQW structure in the short cavity is realized by us, meanwhile the sharpness of the variation depends on spontaneous emission factor.展开更多
The epitaxial growth of novel GaN-based light-emitting diode(LED) on Si(100) substrate has proved challenging.Here in this work, we investigate a monolithic phosphor-free semi-polar InGaN/GaN near white light-emitting...The epitaxial growth of novel GaN-based light-emitting diode(LED) on Si(100) substrate has proved challenging.Here in this work, we investigate a monolithic phosphor-free semi-polar InGaN/GaN near white light-emitting diode, which is formed on a micro-striped Si(100) substrate by metal organic chemical vapor deposition. By controlling the size of micro-stripe, InGaN/GaN multiple quantum wells(MQWs) with different well widths are grown on semi-polar(1■01)planes. Besides, indium-rich quantum dots are observed in InGaN wells by transmission electron microscopy, which is caused by indium phase separation. Due to the different widths of MQWs and indium phase separation, the indium content changes from the center to the side of the micro-stripe. Various indium content provides the wideband emission. This unique property allows the semipolar InGaN/GaN MQWs to emit wideband light, leading to the near white light emission.展开更多
A new approach to fabricating high-quality AlInGaN film as a lattice-matched barrier layer in multiple quantum wells（MQWs） is presented. The high-quality AlInGaN film is realized by growing the AlGaN/InGaN short per...A new approach to fabricating high-quality AlInGaN film as a lattice-matched barrier layer in multiple quantum wells（MQWs） is presented. The high-quality AlInGaN film is realized by growing the AlGaN/InGaN short period superlattices through metalorganic chemical vapor deposition, and then being used as a barrier in the MQWs. The crystalline quality of the MQWs with the lattice-matched AlInGaN barrier and that of the conventional InGaN/GaN MQWs are characterized by x-ray diffraction and scanning electron microscopy. The photoluminescence（PL） properties of the InGaN/AlInGa N MQWs are investigated by varying the excitation power density and temperature through comparing with those of the InGaN/GaN MQWs. The integral PL intensity of InGaN/AlInGaN MQWs is over 3 times higher than that of InGaN/GaN MQWs at room temperature under the highest excitation power. Temperature-dependent PL further demonstrates that the internal quantum efficiency of InGaN/AlInGaN MQWs（76.1%） is much higher than that of InGaN/GaN MQWs（21%）.The improved luminescence performance of InGaN/AlInGaN MQWs can be attributed to the distinct reduction of the barrier-well lattice mismatch and the strain-induced non-radiative recombination centers.展开更多
InGaN/GaN multiple quantum-well(MQW) structures with a wavelength range of green were successfully grown on a c-plane GaN template with SiO_2 stripe patterns along the [11-20] and [1-100] directions as a mask. The sur...InGaN/GaN multiple quantum-well(MQW) structures with a wavelength range of green were successfully grown on a c-plane GaN template with SiO_2 stripe patterns along the [11-20] and [1-100] directions as a mask. The surface morphologies of both samples were investigated using scanning electron microscopy and demonstrated anisotropic growth characteristics of GaN. The optical characteristics were investigated using Raman spectra and photoluminescence(PL). The InGaN/GaN MQW structure grown on the GaN template with SiO_2 stripes along the [1-100] orientation exhibited less stress and higher PL intensity.Transmission electron microscopy results indicated that portions of MQWs were grown on an inclined semipolar plane, and air voids occurred only when the direction of the mask stripe was along the [1-100] orientation. The enhancement of the optical characteristic was due to the air-void structure and inclined semipolar quantum-well sidewalls.展开更多
Structural properties of InxGa_(1−x)N/GaN multi-quantum wells(MQWs)grown on sapphire by metal organic chemical vapor deposition are investigated by synchrotron radiation x-ray diffraction(SRXRD),Rutherford backscatter...Structural properties of InxGa_(1−x)N/GaN multi-quantum wells(MQWs)grown on sapphire by metal organic chemical vapor deposition are investigated by synchrotron radiation x-ray diffraction(SRXRD),Rutherford backscattering/channelling(RBS/C)and high-resolution transmission electron microscopy.The sample consists of eight periods of InxGa_(1−x)N/GaN wells of 2.1 nm thickness and 8.5 nm thickness of GaN barrier,and the results are very close,which verifies the accuracy of the three methods.The indium content in InxGa_(1−x)N/GaN MQWs by SRXRD and RBS/C is estimated,and results are in general the same.By RBS/C random spectra,the indium atomic lattice substitution rate is 94.0%,indicating that almost all indium atoms in InxGa_(1−x)N/GaN MQWs are at substitution,that the indium distribution of each layer in InxGa_(1−x)N/GaN MQWs is very homogeneous and that the InxGa_(1−x)N/GaN MQWs have a very good crystalline quality.It is not accurate to estimate indium content in InxGa_(1−x)N/GaN MQWs by photoluminescence(PL)spectra,because the result from the PL experimental method is very different from the results by the SRXRD and RBS/C experimental methods.展开更多
基金the National Natural Science Foundation of China(Grant No.62074120)the State Key Laboratory on Integrated Optoelectronics(Grant No.IOSKL2018KF10)the Fundamental Research Funds for the Central Universities(Grant No.JB211108).
文摘The nano-patterned InGaN film was used in green InGaN/GaN multiple quantum wells(MQWs)structure,to relieve the unpleasantly existing mismatch between high indium content InGaN and GaN,as well as to enhance the light output.The different self-assembled nano-masks were formed on InGaN by annealing thin Ni layers of different thicknesses.Whereafter,the InGaN films were etched into nano-patterned films.Compared with the green MQWs structure grown on untreated InGaN film,which on nano-patterned InGaN had better luminous performance.Among them the MQWs performed best when 3 nm thick Ni film was used as mask,because that optimally balanced the effects of nano-patterned InGaN on the crystal quality and the light output.
基金Project supported by the National High Technology Research and Development Program of China(No.2006AA03A141)the Knowledge Innovation Engineering of the Chinese Academy of Sciences(No.YYYJ-0701-02)+2 种基金the National Natural Science Foundation of China (Nos.60890193,60906006)the State Key Development Program for Basic Research of China(Nos.2006CB604905,2010CB327503)the Knowledge Innovation Program of the Chinese Academy of Sciences(Nos.ISCAS2008T01,ISCAS2009L01,ISCAS2009L02)
文摘A homemade 7×2 inch MOCVD system is presented.With this system,high quality GaN epitaxial layers,InGaN/GaN multi-quantum wells and blue LED structural epitaxial layers have been successfully grown. The non-uniformity of undoped GaN epitaxial layers is as low as 2.86%.Using the LED structural epitaxial layers, blue LED chips with area of 350×350μm2 were fabricated.Under 20 mA injection current,the optical output power of the blue LED is 8.62 mW.
文摘An analysis solution of rate equation is derived for vertical cavity surface-emitting lasers. Based on the enhanced spontaneous emission caused by VCSELs and influence of nonradiative recombination, the relation between output properties and structural parameters of multi-quantum wells (MQWs) is obtained. It was found that the characteristic curve of a“thresholdless”laser is strongly nonradiative depopulation-dependent. When the nonradiative depopulation is no zero, the light-current characteristic is not linearly even for an ideal closed microcavity. The light output is increased by the enhanced well number and by the reduced width. In particular, a lower threshold current density for MQW structure in the short cavity is realized by us, meanwhile the sharpness of the variation depends on spontaneous emission factor.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51472229,61422405,and 11574301)the Natural Science Foundation of Tianjin(Grant No.14JCQNJC01000)the National Science Foundation for Post-doctoral Scientists of China(Grant No.2016M600231)
文摘The epitaxial growth of novel GaN-based light-emitting diode(LED) on Si(100) substrate has proved challenging.Here in this work, we investigate a monolithic phosphor-free semi-polar InGaN/GaN near white light-emitting diode, which is formed on a micro-striped Si(100) substrate by metal organic chemical vapor deposition. By controlling the size of micro-stripe, InGaN/GaN multiple quantum wells(MQWs) with different well widths are grown on semi-polar(1■01)planes. Besides, indium-rich quantum dots are observed in InGaN wells by transmission electron microscopy, which is caused by indium phase separation. Due to the different widths of MQWs and indium phase separation, the indium content changes from the center to the side of the micro-stripe. Various indium content provides the wideband emission. This unique property allows the semipolar InGaN/GaN MQWs to emit wideband light, leading to the near white light emission.
基金supported by the National Natural Science Foundation of China(Grant Nos.61274003,61422401,51461135002,and 61334009)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BY2013077,BK20141320,BE2015111,and BK20161324)+1 种基金the Program for New Century Excellent Talents in University,China(Grant No.NCET-11-0229)the Special Semiconductor Materials and Devices Research Funds from State Grid Shandong Electric Power Company,China
文摘A new approach to fabricating high-quality AlInGaN film as a lattice-matched barrier layer in multiple quantum wells（MQWs） is presented. The high-quality AlInGaN film is realized by growing the AlGaN/InGaN short period superlattices through metalorganic chemical vapor deposition, and then being used as a barrier in the MQWs. The crystalline quality of the MQWs with the lattice-matched AlInGaN barrier and that of the conventional InGaN/GaN MQWs are characterized by x-ray diffraction and scanning electron microscopy. The photoluminescence（PL） properties of the InGaN/AlInGa N MQWs are investigated by varying the excitation power density and temperature through comparing with those of the InGaN/GaN MQWs. The integral PL intensity of InGaN/AlInGaN MQWs is over 3 times higher than that of InGaN/GaN MQWs at room temperature under the highest excitation power. Temperature-dependent PL further demonstrates that the internal quantum efficiency of InGaN/AlInGaN MQWs（76.1%） is much higher than that of InGaN/GaN MQWs（21%）.The improved luminescence performance of InGaN/AlInGaN MQWs can be attributed to the distinct reduction of the barrier-well lattice mismatch and the strain-induced non-radiative recombination centers.
基金supported by the Key Research and Development Program in Shaanxi Province (Grant Nos. 2018ZDCXL-GY-01-02-02 and 2018ZDCXLGY-01-07)Wuhu and Xidian University Special Fund for Industry University Research Cooperation (Grant No. XWYCXY-012020007)+2 种基金the National Natural Science Foundation of China (Grant No. 62074120)the Fundamental Research Funds for the Central Universitiesthe Innovation Fund of Xidian University。
文摘InGaN/GaN multiple quantum-well(MQW) structures with a wavelength range of green were successfully grown on a c-plane GaN template with SiO_2 stripe patterns along the [11-20] and [1-100] directions as a mask. The surface morphologies of both samples were investigated using scanning electron microscopy and demonstrated anisotropic growth characteristics of GaN. The optical characteristics were investigated using Raman spectra and photoluminescence(PL). The InGaN/GaN MQW structure grown on the GaN template with SiO_2 stripes along the [1-100] orientation exhibited less stress and higher PL intensity.Transmission electron microscopy results indicated that portions of MQWs were grown on an inclined semipolar plane, and air voids occurred only when the direction of the mask stripe was along the [1-100] orientation. The enhancement of the optical characteristic was due to the air-void structure and inclined semipolar quantum-well sidewalls.
基金by the National Natural Science Foundation of China under Grant No 10875004 and 11005005the National Basic Research Program of China under Grant No 2010CB832904.
文摘Structural properties of InxGa_(1−x)N/GaN multi-quantum wells(MQWs)grown on sapphire by metal organic chemical vapor deposition are investigated by synchrotron radiation x-ray diffraction(SRXRD),Rutherford backscattering/channelling(RBS/C)and high-resolution transmission electron microscopy.The sample consists of eight periods of InxGa_(1−x)N/GaN wells of 2.1 nm thickness and 8.5 nm thickness of GaN barrier,and the results are very close,which verifies the accuracy of the three methods.The indium content in InxGa_(1−x)N/GaN MQWs by SRXRD and RBS/C is estimated,and results are in general the same.By RBS/C random spectra,the indium atomic lattice substitution rate is 94.0%,indicating that almost all indium atoms in InxGa_(1−x)N/GaN MQWs are at substitution,that the indium distribution of each layer in InxGa_(1−x)N/GaN MQWs is very homogeneous and that the InxGa_(1−x)N/GaN MQWs have a very good crystalline quality.It is not accurate to estimate indium content in InxGa_(1−x)N/GaN MQWs by photoluminescence(PL)spectra,because the result from the PL experimental method is very different from the results by the SRXRD and RBS/C experimental methods.
