Single crystalline Cr-doped GaN fihns are successfully grown by hydride vapor phase epitaxy. The structure analysis indicates that the film is uniform without detectable Cr precipitates or clusters and the Cr atoms ar...Single crystalline Cr-doped GaN fihns are successfully grown by hydride vapor phase epitaxy. The structure analysis indicates that the film is uniform without detectable Cr precipitates or clusters and the Cr atoms are substituted for Ga sites. The impurity modes in the range 510 530cm^-1 are observed by the Raman spectra. The modes are assigned to the host lattice defects caused by substitutional Cr. The donor-aeceptor emission is found to locate at Ec - 0.20 eV by analyzing the photoluminescence spectrum obtained at different temperatures, and the emission is attributed to the structural defects caused by CrGa-VN complex. The superconductor quantum interference device results show that the Cr-doped GaN film without detectable Cr precipitates or clusters exhibits paramagnetic properties.展开更多
GaN nanowires are grown by hydride vapor phase epitaxy using nickel as a catalyst.The properties of the obtained GaN nanowires are characterized by scanning and transmission electron microscopy,electron diffraction,ro...GaN nanowires are grown by hydride vapor phase epitaxy using nickel as a catalyst.The properties of the obtained GaN nanowires are characterized by scanning and transmission electron microscopy,electron diffraction,roomtemperature photoluminescence and energy dispersive spectroscopy.The results show that the nanowires are wurtzite single crystals growing along the[0001]direction and a redshift in the photoluminescence is observed due to a superposition of several effects.The Raman spectra are close to those of the bulk GaN and the significantly broadening of those modes indicates the phonon confinement effects associated with the nanoscale dimensions of the system.展开更多
Chemical mechanical polishing （CMP） has been used to produce smooth and scratch-free surfaces for GaN. In the aqueous solution of KOH, GaN is subjected to etching. At the same time, all surface irregularities, inclu...Chemical mechanical polishing （CMP） has been used to produce smooth and scratch-free surfaces for GaN. In the aqueous solution of KOH, GaN is subjected to etching. At the same time, all surface irregularities, including etch pyramids, roughness after mechanical polishing and so on will be removed by a polishing pad. The experiments had been performed under the condition of different abrasive particle sizes of the polishing pad. Also the polishing results for different polishing times are analyzed, and chemical mechanical polishing resulted in an average root mean square （RMS） surface roughness of 0.565 nm, as measured by atomic force microscopy.展开更多
基金Supported by the National Basic Research Program of China under Grant No 2011CB301900, the National High-Tech Research and Development Program of China under Grant Nos 2009AA03A198, the National Natural Science Foundation of China under Grant Nos 60990311, 60731160628, 608201060, 60906025, 60820106003 and 60936004, the Natural Science Foundation of Jiangsu Province （BK2008019, BK2009255, BK2010178, BK2010385）, and the Research Funds from NJU-Yangzhou Institute of Optoelectronics.
文摘Single crystalline Cr-doped GaN fihns are successfully grown by hydride vapor phase epitaxy. The structure analysis indicates that the film is uniform without detectable Cr precipitates or clusters and the Cr atoms are substituted for Ga sites. The impurity modes in the range 510 530cm^-1 are observed by the Raman spectra. The modes are assigned to the host lattice defects caused by substitutional Cr. The donor-aeceptor emission is found to locate at Ec - 0.20 eV by analyzing the photoluminescence spectrum obtained at different temperatures, and the emission is attributed to the structural defects caused by CrGa-VN complex. The superconductor quantum interference device results show that the Cr-doped GaN film without detectable Cr precipitates or clusters exhibits paramagnetic properties.
基金Supported by the National Basic Research Program of China(2011CB301900)the National Nature Science Foundation of China(60990311,60820106003,60906025,60936004)+1 种基金the Nature Science Foundation of Jiangsu Province(BK2008019,BK2010385,BK2009255,BK2010178)the Research Funds from NJU-Yangzhou Institute of Opto-electronics.
文摘GaN nanowires are grown by hydride vapor phase epitaxy using nickel as a catalyst.The properties of the obtained GaN nanowires are characterized by scanning and transmission electron microscopy,electron diffraction,roomtemperature photoluminescence and energy dispersive spectroscopy.The results show that the nanowires are wurtzite single crystals growing along the[0001]direction and a redshift in the photoluminescence is observed due to a superposition of several effects.The Raman spectra are close to those of the bulk GaN and the significantly broadening of those modes indicates the phonon confinement effects associated with the nanoscale dimensions of the system.
基金supported by the State Key Development Program for Basic Research of China (No. 2006CB6049)the National HighTechnology Research and Development Program of China (Nos. 2006AA03A103, 2006AA03A118, 006AA03A142, 2006AA03Z411)+2 种基金the National Natural Science Foundation of China (Nos. 60721063, 0731160628, 60776001, 60676057)the Doctoral Special Funds ofUniversity of China (No. 20050284004)the National Foundation for Fostering Talents of Basic Science (No. J0630316).
文摘Chemical mechanical polishing （CMP） has been used to produce smooth and scratch-free surfaces for GaN. In the aqueous solution of KOH, GaN is subjected to etching. At the same time, all surface irregularities, including etch pyramids, roughness after mechanical polishing and so on will be removed by a polishing pad. The experiments had been performed under the condition of different abrasive particle sizes of the polishing pad. Also the polishing results for different polishing times are analyzed, and chemical mechanical polishing resulted in an average root mean square （RMS） surface roughness of 0.565 nm, as measured by atomic force microscopy.
