The influence of the growth temperature,TMIn/TEGa andⅤ/Ⅲratio on the V-defects of InGaN/GaN multi-quantum wells（MQWs） has been investigated and discussed.When the TMIn flow increases from 180 to 200 sccm,the densi...The influence of the growth temperature,TMIn/TEGa andⅤ/Ⅲratio on the V-defects of InGaN/GaN multi-quantum wells（MQWs） has been investigated and discussed.When the TMIn flow increases from 180 to 200 sccm,the density of V-defects increases from 2.72×10^（18） to 5.24×10^（18） cm^（-2）,and the V-defect width and depth increase too.The density also increases with the growth temperature.The densities are 2.05×10~8,2.72×10^（18） and 4.23×10~8 cm^（-2）,corresponding to a growth temperature of 748,753 and 758℃respectively.When the NH_3 flows are 5000,6600 and 8000 sccm,the densities of the V-defects of these samples are 6.34×10^（18）,2.72×10^（18） and 4.13×10^（18） cm^（-2）,respectively.A properⅤ/Ⅲratio is needed to achieve step flow growth mode.We get the best quality of InGaN/GaN MQWs at a growth temperature of 753℃TMIn flow at 180 sccm,NH_3 flow at 6600 sccm,a flatter surface and less V-defects density.The depths of these V-defects are from 10 to 30 nm,and the widths are from 100 to 200 nm.In order to suppress the influence of V-defects on reverse current and electro-static discharge of LEDs,it is essential to grow thicker p-GaN to fill the V-defects.展开更多
InGaN films were deposited on（0001） sapphire substrates with GaN buffer layers under different growth temperatures by metalorganic chemical vapor deposition.The In-composition of InGaN film was approximately control...InGaN films were deposited on（0001） sapphire substrates with GaN buffer layers under different growth temperatures by metalorganic chemical vapor deposition.The In-composition of InGaN film was approximately controlled by changing the growth temperature.The connection between the growth temperature,In content,surface morphology and defect formation was obtained by X-ray diffraction,scanning electron microscopy（SEM） and atomic force microscopy（AFM）.Meanwhile,by comparing the SEM and AFM surface morphology images,we proposed several models of three different defects and discussed the mechanism of formation.The prominent effect of higher growth temperature on the quality of the InGaN films and defect control were found by studying InGaN films at various growth temperatures.展开更多
InA1N has been studied by means of temperature-dependent time-integrated photoluminescence and time-resolved photoluminescence. The variation of PL peak energy did not follow the behavior predicted by Varshni formula,...InA1N has been studied by means of temperature-dependent time-integrated photoluminescence and time-resolved photoluminescence. The variation of PL peak energy did not follow the behavior predicted by Varshni formula, and a faster redshift with increasing temperature was observed. We used a model that took account of the thermal activation and thermal transfer of localized excitons to describe and explain the observed behavior. A good fitting to the experiment result is obtained. We believe the anomalous temperature dependence of PL peak energy shift can be attributed to the temperature-dependent redistribution of localized excitons induced by thermal activation and thermal transfer in the strongly localized states. V-shaped defects are thought to be a major factor causing the strong localized states in our ln0.153Al0.847N sample.展开更多
The advantages of InGaN/GaN light emitting diodes （LEDs） with p-GaN grown under high pressures are studied. It is shown that the high growth pressure could lead to better electronic properties of p-GaN layers due to...The advantages of InGaN/GaN light emitting diodes （LEDs） with p-GaN grown under high pressures are studied. It is shown that the high growth pressure could lead to better electronic properties of p-GaN layers due to the eliminated compensation effect. The contact resistivity of p-GaN layers are decreased due to the reduced donor-like defects on the p-GaN surface. The leakage current is also reduced, which may be induced by the better filling of V-defects with p-GaN layers grown under high pressures. The LED efficiency thus could be enhanced with high pressure grown p-GaN layers.展开更多
We study the interactions of moving discrete solitons in waveguide arrays with two types of point defects that are constructed by varying either the local linear coupling or local waveguide propagation constant at the...We study the interactions of moving discrete solitons in waveguide arrays with two types of point defects that are constructed by varying either the local linear coupling or local waveguide propagation constant at the center of the waveguide array. A broad discrete soliton is kicked toward the defect and interacts with it. Transmission, reflection, scattering, and trapping during the interaction between the soliton and the defect occur depending on the parameters. The detailed behavior of the soliton dynamics is analyzed numerically. A transmission window in the parameter domain is found and the behavior of this window for different parameters is studied. The dynamics of the soliton in the transmission window is found to have chaotic features under certain circumstances and the causes of these phenomena are identified and discussed.展开更多
基金Project supported by the National High Technology Research and Development Program of China(No.2008AA03A197)
文摘The influence of the growth temperature,TMIn/TEGa andⅤ/Ⅲratio on the V-defects of InGaN/GaN multi-quantum wells（MQWs） has been investigated and discussed.When the TMIn flow increases from 180 to 200 sccm,the density of V-defects increases from 2.72×10^（18） to 5.24×10^（18） cm^（-2）,and the V-defect width and depth increase too.The density also increases with the growth temperature.The densities are 2.05×10~8,2.72×10^（18） and 4.23×10~8 cm^（-2）,corresponding to a growth temperature of 748,753 and 758℃respectively.When the NH_3 flows are 5000,6600 and 8000 sccm,the densities of the V-defects of these samples are 6.34×10^（18）,2.72×10^（18） and 4.13×10^（18） cm^（-2）,respectively.A properⅤ/Ⅲratio is needed to achieve step flow growth mode.We get the best quality of InGaN/GaN MQWs at a growth temperature of 753℃TMIn flow at 180 sccm,NH_3 flow at 6600 sccm,a flatter surface and less V-defects density.The depths of these V-defects are from 10 to 30 nm,and the widths are from 100 to 200 nm.In order to suppress the influence of V-defects on reverse current and electro-static discharge of LEDs,it is essential to grow thicker p-GaN to fill the V-defects.
基金Project supported by the Special Funds for Major State Basic Research Project,China(No.2011CB301900)the Hi-Tech Research Project (No.2009AA03A198)+2 种基金the National Natural Science Foundation of China(Nos.60990311,60721063,60906025,60936004)the Natural Science Foundation of Jiangsu Province,China(Nos.BK2008019,BK2009255,BK2010178)the Research Funds from NJU-Yangzhou Institute of Opto-Electronics,China
文摘InGaN films were deposited on（0001） sapphire substrates with GaN buffer layers under different growth temperatures by metalorganic chemical vapor deposition.The In-composition of InGaN film was approximately controlled by changing the growth temperature.The connection between the growth temperature,In content,surface morphology and defect formation was obtained by X-ray diffraction,scanning electron microscopy（SEM） and atomic force microscopy（AFM）.Meanwhile,by comparing the SEM and AFM surface morphology images,we proposed several models of three different defects and discussed the mechanism of formation.The prominent effect of higher growth temperature on the quality of the InGaN films and defect control were found by studying InGaN films at various growth temperatures.
基金Project supported by the National Basic Research Program of China(No.2012CB619306)
文摘InA1N has been studied by means of temperature-dependent time-integrated photoluminescence and time-resolved photoluminescence. The variation of PL peak energy did not follow the behavior predicted by Varshni formula, and a faster redshift with increasing temperature was observed. We used a model that took account of the thermal activation and thermal transfer of localized excitons to describe and explain the observed behavior. A good fitting to the experiment result is obtained. We believe the anomalous temperature dependence of PL peak energy shift can be attributed to the temperature-dependent redistribution of localized excitons induced by thermal activation and thermal transfer in the strongly localized states. V-shaped defects are thought to be a major factor causing the strong localized states in our ln0.153Al0.847N sample.
文摘The advantages of InGaN/GaN light emitting diodes （LEDs） with p-GaN grown under high pressures are studied. It is shown that the high growth pressure could lead to better electronic properties of p-GaN layers due to the eliminated compensation effect. The contact resistivity of p-GaN layers are decreased due to the reduced donor-like defects on the p-GaN surface. The leakage current is also reduced, which may be induced by the better filling of V-defects with p-GaN layers grown under high pressures. The LED efficiency thus could be enhanced with high pressure grown p-GaN layers.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant Nos. 11104083, 11204089, and 61172011）.
文摘We study the interactions of moving discrete solitons in waveguide arrays with two types of point defects that are constructed by varying either the local linear coupling or local waveguide propagation constant at the center of the waveguide array. A broad discrete soliton is kicked toward the defect and interacts with it. Transmission, reflection, scattering, and trapping during the interaction between the soliton and the defect occur depending on the parameters. The detailed behavior of the soliton dynamics is analyzed numerically. A transmission window in the parameter domain is found and the behavior of this window for different parameters is studied. The dynamics of the soliton in the transmission window is found to have chaotic features under certain circumstances and the causes of these phenomena are identified and discussed.
