High-quality and nearly crack-free GaN epitaxial layer was obtained by inserting a single A1GaN interlayer between GaN epilayer and high-temperature AlN buffer layer on Si （111） substrate by metalorganic chemical va...High-quality and nearly crack-free GaN epitaxial layer was obtained by inserting a single A1GaN interlayer between GaN epilayer and high-temperature AlN buffer layer on Si （111） substrate by metalorganic chemical vapor deposition. This paper investigates the effect of AlCaN interlayer on the structural properties of the resulting CaN epilayer. It confirms from the optical microscopy and Raman scattering spectroscopy that the AIGaN interlayer has a remarkable effect on introducing relative compressive strain to the top GaN layer and preventing the formation of cracks. X-ray diffraction and transmission electron microscopy analysis reveal that a significant reduction in both screw and edge threading dislocations is achieved in GaN epilayer by the insertion of AlGaN interlayer. The process of threading dislocation reduction in both AlGaN interlayer and GaN epilayer is demonstrated.展开更多
We have investigated the electron affinity of Si-doped AlN films（N_（Si）= 1.0 × 10^（18）–1.0 × 10_（19）cm^（-3）） with thicknesses of 50, 200, and 400 nm, synthesized by metalorganic chemical vapor dep...We have investigated the electron affinity of Si-doped AlN films（N_（Si）= 1.0 × 10^（18）–1.0 × 10_（19）cm^（-3）） with thicknesses of 50, 200, and 400 nm, synthesized by metalorganic chemical vapor deposition（MOCVD） under low pressure on the ntype（001）6H–SiC substrates. The positive and small electron affinity of AlN films was observed through the ultraviolet photoelectron spectroscopy（UPS） analysis, where an increase in electron affinity appears with the thickness of AlN films increasing, i.e., 0.36 eV for the 50-nm-thick one, 0.58 eV for the 200-nm-thick one, and 0.97 e V for the 400-nm-thick one.Accompanying the x-ray photoelectron spectroscopy（XPS） analysis on the surface contaminations, it suggests that the difference of electron affinity between our three samples may result from the discrepancy of surface impurity contaminations.展开更多
The effects of V/Ill growth flux ratio on a-plane GaN films grown on r-plane sapphire substrates with an InGaN interlayer are investigated. The surface morphology, crystalline quality, strain states, and density of ba...The effects of V/Ill growth flux ratio on a-plane GaN films grown on r-plane sapphire substrates with an InGaN interlayer are investigated. The surface morphology, crystalline quality, strain states, and density of basal stacking faults were found to depend heavily upon the V/III ratio. With decreasing V/III ratio, the surface morphology and crystal quality first improved and then deteriorated, and the density of the basal-plane stacking faults also first decreased and then increased. The optimal V/III ratio growth condition for the best surface morphology and crystalline quality and the smallest basal-plane stacking fault density of a-GaN films are found. We also found that the formation of basal-plane stacking faults is an effective way to release strain.展开更多
Pure zinc blende GaAs nanowires were grown by metal organic chemical vapor deposition on GaAs（111） B substrates via Au catalyzed vapor-liquid-solid mechanism.We found that the grown nanowires are rod-like in shape a...Pure zinc blende GaAs nanowires were grown by metal organic chemical vapor deposition on GaAs（111） B substrates via Au catalyzed vapor-liquid-solid mechanism.We found that the grown nanowires are rod-like in shape and have a pure zinc blende structure;moreover,the growth rate is independent on its diameters.It can be concluded that, direct impingement of vapor species onto the Au-Ga droplets contributes to the growth of the nanowire;in contrast,the adatom diffusion makes little contribution.The results indicate that the droplet acts as a catalyst rather than an adatom collector,larger diameter and high supersatuation in the droplet leads to the pure zinc blende structure of the nanowire.展开更多
InN films grown on sapphire at different substrate temperatures from 550°C to 700°C by metalorganic chemical vapor deposition were investigated. The low-temperature GaN nucleation layer with high-temperature...InN films grown on sapphire at different substrate temperatures from 550°C to 700°C by metalorganic chemical vapor deposition were investigated. The low-temperature GaN nucleation layer with high-temperature annealing (1100°C) was used as a buffer for main InN layer growth. X-ray diffraction and Raman scattering measurements reveal that the quality of InN films can be improved by increasing the growth temperature to 600°C. Further high substrate temperatures may promote the thermal decomposition of InN films and result in poor crystallinity and surface morphology. The photoluminescence and Hall measurements were employed to characterize the optical and electrical properties of InN films, which also indicates strong growth temperature dependence. The InN films grown at temperature of 600°C show not only a high mobility with low carrier concentration, but also a strong infrared emission band located around 0.7 eV. For a 600 nm thick InN film grown at 600°C, the Hall mobility achieves up to 938 cm2/Vs with electron concentration of 3.9 × 1018 cm?3.展开更多
In this paper,we use the a-plane InGaN interlayer to improve the property of a-plane GaN.Based on the a-InGaN interlayer,a template exhibits that a regular,porous structure,which acts as a compliant effect,can be obta...In this paper,we use the a-plane InGaN interlayer to improve the property of a-plane GaN.Based on the a-InGaN interlayer,a template exhibits that a regular,porous structure,which acts as a compliant effect,can be obtained to release the strain caused by the lattice and thermal mismatch between a-GaN and r-sapphire.We find that the thickness of InGaN has a great influence on the growth of a-GaN.The surface morphology and crystalline quality both are first improved and then deteriorated with increasing the thickness of the InGaN interlayer.When the InGaN thickness exceeds a critical point,the a-GaN epilayer peels off in the process of cooling down to room temperature.This is an attractive way of lifting off a-GaN films from the sapphire substrate.展开更多
The aluminum incorporation efficiencies in nonpolar A-plane and polar C-plane A1GaN films grown by metalorganic vapour phase epitaxy （MOVPE） are investigated. It is found that the aluminum content in A-plane A1GaN f...The aluminum incorporation efficiencies in nonpolar A-plane and polar C-plane A1GaN films grown by metalorganic vapour phase epitaxy （MOVPE） are investigated. It is found that the aluminum content in A-plane A1GaN film is obviously higher than that in the C-plane sample when the growth temperature is above 1070 ℃. The high aluminum incorporation efficiency is beneficial to fabricating deep ultraviolet optoelectronic devices. Moreover, the influences of the gas inlet ratio, the V/Ⅲ ratio, and the chamber pressure on the aluminum content are studied. The results are important for growing the A1GaN films, especially nonpolar A1GaN epilayers.展开更多
Semi-polar （1 - 101 ） InGaN/GaN light-emitting diodes were prepared on standard electronic-grade Si （100） substrates. Micro-stripes of GaN and InGaN/GaN quantum wells on semi-polar facets were grown on intersectin...Semi-polar （1 - 101 ） InGaN/GaN light-emitting diodes were prepared on standard electronic-grade Si （100） substrates. Micro-stripes of GaN and InGaN/GaN quantum wells on semi-polar facets were grown on intersecting { 111 } planes of microscale V-grooved Si in metal-organic vapor phase epitaxy, covering over 50% of the wafer surface area. In-situ optical reflectivity and curvature measurements demonstrate that the effect of the thermal expansion coefficient mismatch was greatly reduced. A cross-sectional analysis reveals low threading dislocation density on the top of most surfaces. On such prepared （1-101） GaN, an InGaN/GaN LED was fabricated. Electroluminescence over 5 mA to 60 mA is found with a much lower blue-shift than that on the c-plane device. Such structures therefore could allow higher efficiency light emitters with a weak quantum confined Stark effect throughout the visible spectrum.展开更多
基金supported by the National Natural Science Foundation of China(61925110,U20A20207,61821091,62004184,62004186,62171426,51932004,and 51961145110)the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(XDB44000000)+4 种基金the Key Research Program of Frontier Sciences of CAS(QYZDB-SSW-JSC048)the Key-Area Research and Development Program of Guangdong Province(2020B010174002)the Fundamental Research Plan(JCKY2020110B010)the CAS Project for Young Scientists in Basic Research(YSBR-029)the Key Laboratory of Nanodevices and Applications at Suzhou Institute of Nano-Tech and Nano-Bionics of CAS。
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60506001, 60476021, 60576003, 60776047 and 60836003)the National Basic Research Program of China (Grant No 2007CB936700)Project of Technological Research and Development of Hebei Province (Grant No 07215134)
文摘High-quality and nearly crack-free GaN epitaxial layer was obtained by inserting a single A1GaN interlayer between GaN epilayer and high-temperature AlN buffer layer on Si （111） substrate by metalorganic chemical vapor deposition. This paper investigates the effect of AlCaN interlayer on the structural properties of the resulting CaN epilayer. It confirms from the optical microscopy and Raman scattering spectroscopy that the AIGaN interlayer has a remarkable effect on introducing relative compressive strain to the top GaN layer and preventing the formation of cracks. X-ray diffraction and transmission electron microscopy analysis reveal that a significant reduction in both screw and edge threading dislocations is achieved in GaN epilayer by the insertion of AlGaN interlayer. The process of threading dislocation reduction in both AlGaN interlayer and GaN epilayer is demonstrated.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61574135,61574134,61474142,61474110,61377020,61376089,61223005,and 61321063)the One Hundred Person Project of the Chinese Academy of Sciencesthe Basic Research Project of Jiangsu Province,China(Grant No.BK20130362)
文摘We have investigated the electron affinity of Si-doped AlN films（N_（Si）= 1.0 × 10^（18）–1.0 × 10_（19）cm^（-3）） with thicknesses of 50, 200, and 400 nm, synthesized by metalorganic chemical vapor deposition（MOCVD） under low pressure on the ntype（001）6H–SiC substrates. The positive and small electron affinity of AlN films was observed through the ultraviolet photoelectron spectroscopy（UPS） analysis, where an increase in electron affinity appears with the thickness of AlN films increasing, i.e., 0.36 eV for the 50-nm-thick one, 0.58 eV for the 200-nm-thick one, and 0.97 e V for the 400-nm-thick one.Accompanying the x-ray photoelectron spectroscopy（XPS） analysis on the surface contaminations, it suggests that the difference of electron affinity between our three samples may result from the discrepancy of surface impurity contaminations.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.91233111,61274041,11275228,61006004,and 61076001)the Special Funds for Major State Basic Research Project (973 Program) of China (Grant No.2012CB619305)+1 种基金the 863 High Technology R&D Program of China (Grant No.2011AA03A101)the Special Fund for LED Industrial Development of Guangdong Province of China (Grant No.2012A080302003)
文摘The effects of V/Ill growth flux ratio on a-plane GaN films grown on r-plane sapphire substrates with an InGaN interlayer are investigated. The surface morphology, crystalline quality, strain states, and density of basal stacking faults were found to depend heavily upon the V/III ratio. With decreasing V/III ratio, the surface morphology and crystal quality first improved and then deteriorated, and the density of the basal-plane stacking faults also first decreased and then increased. The optimal V/III ratio growth condition for the best surface morphology and crystalline quality and the smallest basal-plane stacking fault density of a-GaN films are found. We also found that the formation of basal-plane stacking faults is an effective way to release strain.
基金Project supported by the Basic Research on Compatible Heterogeneous Integration and Functional-Microstructure Assemblage for the Development of Novel Optoelectronic Devices,China(No.2010CB327600)the 111 Program of China(No.B07005),the Program of Key International Science and Technology Cooperation Projects(No.2006DFB 11110)+3 种基金the New Century Excellent Talents in University (NCET-08-0736)the National High Technology R & D Program of China(Nos.2009AA03Z405,2009AA03Z417)the Chinese Universities Scientific Fund(Nos.BUPT2009RC0409,BUPT2009RC0410)the Program for Changjiang Scholars and Innovative Research Team in University,MOE(No.IRT0609).
文摘Pure zinc blende GaAs nanowires were grown by metal organic chemical vapor deposition on GaAs（111） B substrates via Au catalyzed vapor-liquid-solid mechanism.We found that the grown nanowires are rod-like in shape and have a pure zinc blende structure;moreover,the growth rate is independent on its diameters.It can be concluded that, direct impingement of vapor species onto the Au-Ga droplets contributes to the growth of the nanowire;in contrast,the adatom diffusion makes little contribution.The results indicate that the droplet acts as a catalyst rather than an adatom collector,larger diameter and high supersatuation in the droplet leads to the pure zinc blende structure of the nanowire.
基金the National Basic Research Program of China (Grant No. 2006CB6049)the National Natural Science Foundation of China (Grant Nos. 6039072, 60476030 and 60421003)+2 种基金the Great Fund of the Ministry of Education of China (Grant No. 10416)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050284004)the Natural Science Foundation of Jiangsu Province of China (Grant Nos. BK2005210 and BK2006126)
文摘InN films grown on sapphire at different substrate temperatures from 550°C to 700°C by metalorganic chemical vapor deposition were investigated. The low-temperature GaN nucleation layer with high-temperature annealing (1100°C) was used as a buffer for main InN layer growth. X-ray diffraction and Raman scattering measurements reveal that the quality of InN films can be improved by increasing the growth temperature to 600°C. Further high substrate temperatures may promote the thermal decomposition of InN films and result in poor crystallinity and surface morphology. The photoluminescence and Hall measurements were employed to characterize the optical and electrical properties of InN films, which also indicates strong growth temperature dependence. The InN films grown at temperature of 600°C show not only a high mobility with low carrier concentration, but also a strong infrared emission band located around 0.7 eV. For a 600 nm thick InN film grown at 600°C, the Hall mobility achieves up to 938 cm2/Vs with electron concentration of 3.9 × 1018 cm?3.
基金supported by the National Natural Science Foundation of China(Grant Nos.91233111,61274041,and 11275228)the Special Funds for Major State Basic Research Project of China(Grant No.2012CB619305)+1 种基金the National High Technology R&D Program of China(Grant Nos.2014AA032603 and2014AA032609)the Guangdong Provincial Special Fund for LED Industrial Development,China(Grant No.2012A080302003)
文摘In this paper,we use the a-plane InGaN interlayer to improve the property of a-plane GaN.Based on the a-InGaN interlayer,a template exhibits that a regular,porous structure,which acts as a compliant effect,can be obtained to release the strain caused by the lattice and thermal mismatch between a-GaN and r-sapphire.We find that the thickness of InGaN has a great influence on the growth of a-GaN.The surface morphology and crystalline quality both are first improved and then deteriorated with increasing the thickness of the InGaN interlayer.When the InGaN thickness exceeds a critical point,the a-GaN epilayer peels off in the process of cooling down to room temperature.This is an attractive way of lifting off a-GaN films from the sapphire substrate.
基金supported by the National Natural Science Foundation of China(Grant Nos.61504128,61504129,61274041,and 11275228)the National Basic Research Program of China(Grant No.2012CB619305)+1 种基金the National High Technology Research and Development Program of China(Grant Nos.2014AA032603,2014AA032609,and 2015AA010801)the Guangdong Provincial Scientific and Technologic Planning Program,China(Grant No.2014B010119002)
文摘The aluminum incorporation efficiencies in nonpolar A-plane and polar C-plane A1GaN films grown by metalorganic vapour phase epitaxy （MOVPE） are investigated. It is found that the aluminum content in A-plane A1GaN film is obviously higher than that in the C-plane sample when the growth temperature is above 1070 ℃. The high aluminum incorporation efficiency is beneficial to fabricating deep ultraviolet optoelectronic devices. Moreover, the influences of the gas inlet ratio, the V/Ⅲ ratio, and the chamber pressure on the aluminum content are studied. The results are important for growing the A1GaN films, especially nonpolar A1GaN epilayers.
文摘Semi-polar （1 - 101 ） InGaN/GaN light-emitting diodes were prepared on standard electronic-grade Si （100） substrates. Micro-stripes of GaN and InGaN/GaN quantum wells on semi-polar facets were grown on intersecting { 111 } planes of microscale V-grooved Si in metal-organic vapor phase epitaxy, covering over 50% of the wafer surface area. In-situ optical reflectivity and curvature measurements demonstrate that the effect of the thermal expansion coefficient mismatch was greatly reduced. A cross-sectional analysis reveals low threading dislocation density on the top of most surfaces. On such prepared （1-101） GaN, an InGaN/GaN LED was fabricated. Electroluminescence over 5 mA to 60 mA is found with a much lower blue-shift than that on the c-plane device. Such structures therefore could allow higher efficiency light emitters with a weak quantum confined Stark effect throughout the visible spectrum.
