In this paper,we simulate a new style vertical HVPE reactor by using computational fluid dynamics program FLUENT.In order to find the best parameter on the growth rate of Gallium nitride(GaN),we change the distance be...In this paper,we simulate a new style vertical HVPE reactor by using computational fluid dynamics program FLUENT.In order to find the best parameter on the growth rate of Gallium nitride(GaN),we change the distance between the inlet and the substrate,GaCl and NH3 inlets,and also we add substrate rotation separately.With the increase of the distance between the substrate and the gas inlet,GaN deposition rate decreases and the uniformity becomes better.The results show that the optimal distance in this new-style vertical hydride vapour phase epitaxy(HVPE) system is 4 cm.Besides,as the distance between the GaCl inlet and the NH3 inlet changes,the uniformity of GaN deposition varies.Our findings indicate that the optimal distance is 3 cm.Furthermore,it is found that substrate rotation also affects the growth rate of GaN.展开更多
In our experiments,the PL spectra of several In x Ga 1 x N alloy samples with In contents x=0.1,0.15 and 0.25 were measured as a function of temperature ranging from 10 K to 300 K.S-shaped temperature dependencies wer...In our experiments,the PL spectra of several In x Ga 1 x N alloy samples with In contents x=0.1,0.15 and 0.25 were measured as a function of temperature ranging from 10 K to 300 K.S-shaped temperature dependencies were observed in all InGaN samples and a sharp decrease in the full width at half maximum occurred with decreasing temperature in the moderate temperature region.It was found that both phenomena are relative to localization effects.In addition,the degree of localization effects in three samples was investigated using the band-tail model.Our findings are presented in this paper.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
The surface morphology,electrical properties and optical properties of Si doped n-type GaN were investigated. The intentional SiH4 doped GaN films were grown by metal organic chemical vapor deposition with the electro...The surface morphology,electrical properties and optical properties of Si doped n-type GaN were investigated. The intentional SiH4 doped GaN films were grown by metal organic chemical vapor deposition with the electron concentration varying from 3×1016 cm-3 to 5.4×1018 cm-3. The surface morphology shows that the roughness and dislocation pits increase as the mass flow rate of SiH4 increases,which indicates that the quality of GaN degrades gradually. The activation energy of Si in GaN with different n concentrations varies from 12 to 22 meV,which may originate from the interactions of donor wave functions. The carrier transport mechanism with increasing temperature from 100 to 420 K was concluded as the complex effect of both impurity scattering and phonon scattering. The position of the near band edge emission peak was determined by both renormalization of the band gap and B-M effect. The intensity variations of the yellow luminescence could be explained by the change of Ga vacancy concentration caused by Si doping.展开更多
基金supported by the National Basic Research Program of China(Grant No.2011CB301900)the National Natural Science Foundation of China(Grant Nos.60990311,60820106003,60906025 and 60936004)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant Nos. BK2008019,BK2010385,BK2009255 and BK2010178)the Research Funds from NJU-Yangzhou Institute of Opto-electronics
文摘In this paper,we simulate a new style vertical HVPE reactor by using computational fluid dynamics program FLUENT.In order to find the best parameter on the growth rate of Gallium nitride(GaN),we change the distance between the inlet and the substrate,GaCl and NH3 inlets,and also we add substrate rotation separately.With the increase of the distance between the substrate and the gas inlet,GaN deposition rate decreases and the uniformity becomes better.The results show that the optimal distance in this new-style vertical hydride vapour phase epitaxy(HVPE) system is 4 cm.Besides,as the distance between the GaCl inlet and the NH3 inlet changes,the uniformity of GaN deposition varies.Our findings indicate that the optimal distance is 3 cm.Furthermore,it is found that substrate rotation also affects the growth rate of GaN.
基金supported by the Special Funds for Major State Basic Research Project (Grant No. 2011CB301901)the National Natural Science Foundation of China (Grant Nos. 60820106003,60990311 and 60906025)+1 种基金the Natural Science Foundation of Jiangsu Province (Grant Nos.BK2008019 and BK2009255)the Research Funds from NJU-Yangzhou Institute of Opto-electronics
文摘In our experiments,the PL spectra of several In x Ga 1 x N alloy samples with In contents x=0.1,0.15 and 0.25 were measured as a function of temperature ranging from 10 K to 300 K.S-shaped temperature dependencies were observed in all InGaN samples and a sharp decrease in the full width at half maximum occurred with decreasing temperature in the moderate temperature region.It was found that both phenomena are relative to localization effects.In addition,the degree of localization effects in three samples was investigated using the band-tail model.Our findings are presented in this paper.
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the National Basic Research Program of China (Grant No. 2006CB6049)the National Hi-Tech Research and Development Program of China (Grant No. 2006AA03A142)+2 种基金the National Natural Science Foundation of China (Grant Nos. 60721063, 60731160628 and 60676057)the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050284004) the Natural Science Foundation of Jiangsu Province of China (Grant No. BK2005210)
文摘The surface morphology,electrical properties and optical properties of Si doped n-type GaN were investigated. The intentional SiH4 doped GaN films were grown by metal organic chemical vapor deposition with the electron concentration varying from 3×1016 cm-3 to 5.4×1018 cm-3. The surface morphology shows that the roughness and dislocation pits increase as the mass flow rate of SiH4 increases,which indicates that the quality of GaN degrades gradually. The activation energy of Si in GaN with different n concentrations varies from 12 to 22 meV,which may originate from the interactions of donor wave functions. The carrier transport mechanism with increasing temperature from 100 to 420 K was concluded as the complex effect of both impurity scattering and phonon scattering. The position of the near band edge emission peak was determined by both renormalization of the band gap and B-M effect. The intensity variations of the yellow luminescence could be explained by the change of Ga vacancy concentration caused by Si doping.
