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
Room-temperature ferromagnetism has been experimentally observed in annealed rutile TiO2 single crystals when a magnetic field is applied parallel to the sample plane.By combining X-ray absorption near the edge struct...Room-temperature ferromagnetism has been experimentally observed in annealed rutile TiO2 single crystals when a magnetic field is applied parallel to the sample plane.By combining X-ray absorption near the edge structure spectrum and positron annihilation lifetime spectroscopy,Ti^3＋-V O defect complexes（or clusters） have been identified in annealed crystals at a high vacuum.We elucidate that the unpaired 3d electrons in Ti^3＋ ions provide the observed room-temperature ferromagnetism.In addition,excess oxygen ions in the TiO2 lattice could induce a number of Ti vacancies which obviously increase magnetic moments.展开更多
目的:寻找一种少磨牙体修复前牙切缘V形缺损的方法。方法:采用登士柏公司生产的Prime & Bond NT粘结剂和DyractAP复合体修复前牙切缘V形缺损。结果:半年内修复成功率95.93%,二年后成功率为88.62%。结论:DyractAP粘结性强、耐磨、色...目的:寻找一种少磨牙体修复前牙切缘V形缺损的方法。方法:采用登士柏公司生产的Prime & Bond NT粘结剂和DyractAP复合体修复前牙切缘V形缺损。结果:半年内修复成功率95.93%,二年后成功率为88.62%。结论:DyractAP粘结性强、耐磨、色泽好,适用于前牙切缘V形缺损的修复。展开更多
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Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61006066)the National Natural Science Foundation of China (Grant No. 11175191)
文摘Room-temperature ferromagnetism has been experimentally observed in annealed rutile TiO2 single crystals when a magnetic field is applied parallel to the sample plane.By combining X-ray absorption near the edge structure spectrum and positron annihilation lifetime spectroscopy,Ti^3＋-V O defect complexes（or clusters） have been identified in annealed crystals at a high vacuum.We elucidate that the unpaired 3d electrons in Ti^3＋ ions provide the observed room-temperature ferromagnetism.In addition,excess oxygen ions in the TiO2 lattice could induce a number of Ti vacancies which obviously increase magnetic moments.
文摘目的:寻找一种少磨牙体修复前牙切缘V形缺损的方法。方法:采用登士柏公司生产的Prime & Bond NT粘结剂和DyractAP复合体修复前牙切缘V形缺损。结果:半年内修复成功率95.93%,二年后成功率为88.62%。结论:DyractAP粘结性强、耐磨、色泽好,适用于前牙切缘V形缺损的修复。
