ZnO quantum dots (QDs)with the sizes of 3.0-5.6 nm are synthesized by solution-phase method at different temperatures. We find that temperature has great influence on the size of ZnO QDs. The growth process is the mos...ZnO quantum dots (QDs)with the sizes of 3.0-5.6 nm are synthesized by solution-phase method at different temperatures. We find that temperature has great influence on the size of ZnO QDs. The growth process is the most sensitive to temperature, and the process is well explained by Lifshitz–Slyozov–Wagner (LSW) model. By photoluminescence (PL) spectra of the quantum dots at different temperatures and reactive time, we come to a conclusion that ultraviolet emission is mainly due to surface defects, and the or...展开更多
The free-standing diamond films are deposited on molybdenum substrate by direct current jet chemical vapor deposition (DCJCVD). X-ray diffraction,Raman spectroscopy and cathodoluminescence (CL) measurement are used to...The free-standing diamond films are deposited on molybdenum substrate by direct current jet chemical vapor deposition (DCJCVD). X-ray diffraction,Raman spectroscopy and cathodoluminescence (CL) measurement are used to investigate the films structure and defects related to electron transition properties of the diamond films. The X-ray diffraction spectrum reveals that the diamond films have the polycrystalline cubic structure with diffraction peaks at 43.88o and 75.24o. A sharp peak at 1331.8 cm-1 and a broad band at about 1250-1550 cm-1 from Raman spectrum are attributed to diamond phase and sp2-type carbons,respectively. Two emission peaks at 440 nm and 530 nm,associated with dislocation defects and nitrogen and vacancy complexes respectively,are observed in cathodoluminescence spectrum. In addition,in order to understand both emission processes,a simple energy level scheme is suggested.展开更多
基金supported in part by National Natural Science Foundation of China(Grant No.60877029)supported by the Tianjin Natural Science Foundation (Grant No.07JCYBJC0640006TXTJJC14600)supported by the Subject of Science and Technology Development Fund at University of Tianjin (Grant No.20071207)
文摘ZnO quantum dots (QDs)with the sizes of 3.0-5.6 nm are synthesized by solution-phase method at different temperatures. We find that temperature has great influence on the size of ZnO QDs. The growth process is the most sensitive to temperature, and the process is well explained by Lifshitz–Slyozov–Wagner (LSW) model. By photoluminescence (PL) spectra of the quantum dots at different temperatures and reactive time, we come to a conclusion that ultraviolet emission is mainly due to surface defects, and the or...
基金supported by the Natural Science Foundation of Tianjin (No. 06YFJZJC00100)
文摘The free-standing diamond films are deposited on molybdenum substrate by direct current jet chemical vapor deposition (DCJCVD). X-ray diffraction,Raman spectroscopy and cathodoluminescence (CL) measurement are used to investigate the films structure and defects related to electron transition properties of the diamond films. The X-ray diffraction spectrum reveals that the diamond films have the polycrystalline cubic structure with diffraction peaks at 43.88o and 75.24o. A sharp peak at 1331.8 cm-1 and a broad band at about 1250-1550 cm-1 from Raman spectrum are attributed to diamond phase and sp2-type carbons,respectively. Two emission peaks at 440 nm and 530 nm,associated with dislocation defects and nitrogen and vacancy complexes respectively,are observed in cathodoluminescence spectrum. In addition,in order to understand both emission processes,a simple energy level scheme is suggested.
