Nickel nanometer catalyst thin films were prepared on SiO2/Si substrates using sputtering coater. The effects of ammonia pretreatment on the catalyst films from continuous film to the nanoparticles were investigated. ...Nickel nanometer catalyst thin films were prepared on SiO2/Si substrates using sputtering coater. The effects of ammonia pretreatment on the catalyst films from continuous film to the nanoparticles were investigated. The nanostructures of the Ni thin films as a function of the catalyst film original thickness, the pretreatment time and temperature were discussed. The optimum parameters of etching process were obtained, and the functional mechanism of ammonia was primarily analyzed. Scanning electron microscopy （SEM） and atomic force microscopy （AFM） were used to evaluate the obtained nanoparticles. It is demonstrated that the controlled size and density distribution of the nanoparticles can be achieved by employing ammonia etching method.展开更多
The etching effect of ammonia （NH3） on the growth of vertically aligned nanotubes/nanofibers （CNTs） was investigated by direct-current plasma enhanced chemical vapor deposition （DC-PECVD）. NH3 gas etches Ni cata...The etching effect of ammonia （NH3） on the growth of vertically aligned nanotubes/nanofibers （CNTs） was investigated by direct-current plasma enhanced chemical vapor deposition （DC-PECVD）. NH3 gas etches Ni catalyst layer to form nanoscale islands while NH3 plasma etches the deposited amorphous carbon. Based on the etching effect of NH3 gas on Ni catalyst, the differences of growing bundles of CNTs and single strand CNTs were discussed; specifically, the amount of optimal NH3 gas etching is different between bundles of CNTs and single strand CNTs. In contrast to the CNT carpet growth, the single strand CNT growth requires shorter etching time （5 min） than large catalytic patterns （10 rain） since nano dots already form catalyst islands for CNT growth. Through removing the plasma pretreatment process, the damage from being exposed at high temperature substrate occurring during the plasma generation time is minimized. High resolution transmission electron microscopy （HTEM） shows fishbone structure of CNTs grown by PECVD.展开更多
Uniform GaN nanopillar arrays have been successfully fabricated by inductively coupled plasma etching using self-organized nickel nano-islands as the masks on GaN/sapphire. GaN nanopillars with diameters of 350 nm and...Uniform GaN nanopillar arrays have been successfully fabricated by inductively coupled plasma etching using self-organized nickel nano-islands as the masks on GaN/sapphire. GaN nanopillars with diameters of 350 nm and densities of 2.6 × 10^8 cm^-2 were demonstrated and controlled by the thickness of Ni film and the NH3 annealing time. These GaN nanopillars show improved optical properties and strain change compared to that of GaN film before ICP etching. Such structures with large-area uniformity and high density could provide additional advantages for light emission of light-emitting diodes, quality improvement of ELO regrowth, etc.展开更多
基金Funded by the State Key Program of National Natural Science Foundation of China (No. 50435030)the National Natural Science Foundation of China (No. 50775104)
文摘Nickel nanometer catalyst thin films were prepared on SiO2/Si substrates using sputtering coater. The effects of ammonia pretreatment on the catalyst films from continuous film to the nanoparticles were investigated. The nanostructures of the Ni thin films as a function of the catalyst film original thickness, the pretreatment time and temperature were discussed. The optimum parameters of etching process were obtained, and the functional mechanism of ammonia was primarily analyzed. Scanning electron microscopy （SEM） and atomic force microscopy （AFM） were used to evaluate the obtained nanoparticles. It is demonstrated that the controlled size and density distribution of the nanoparticles can be achieved by employing ammonia etching method.
基金Project supported by Intelligent Microsystem Center(IMC)Project(2010-0008-276) supported by the National Core Research Center through the National Research Foundation of Korea funded by the Ministry of Education, Science and TechnologyProject(2010) supported by Pusan National University
文摘The etching effect of ammonia （NH3） on the growth of vertically aligned nanotubes/nanofibers （CNTs） was investigated by direct-current plasma enhanced chemical vapor deposition （DC-PECVD）. NH3 gas etches Ni catalyst layer to form nanoscale islands while NH3 plasma etches the deposited amorphous carbon. Based on the etching effect of NH3 gas on Ni catalyst, the differences of growing bundles of CNTs and single strand CNTs were discussed; specifically, the amount of optimal NH3 gas etching is different between bundles of CNTs and single strand CNTs. In contrast to the CNT carpet growth, the single strand CNT growth requires shorter etching time （5 min） than large catalytic patterns （10 rain） since nano dots already form catalyst islands for CNT growth. Through removing the plasma pretreatment process, the damage from being exposed at high temperature substrate occurring during the plasma generation time is minimized. High resolution transmission electron microscopy （HTEM） shows fishbone structure of CNTs grown by PECVD.
基金Project supported by the Special Funds for Major State Basic Research Project(Nos.2011CB301900,2012CB619304,2010CB327504)the Hi-Tech Research Project(No.2011AA03A103)+1 种基金the National Natural Science Foundation of China(Nos.60990311,61274003,60936004,61176063)the Natural Science Foundation of Jiangsu Province(No.BK2011010)
文摘Uniform GaN nanopillar arrays have been successfully fabricated by inductively coupled plasma etching using self-organized nickel nano-islands as the masks on GaN/sapphire. GaN nanopillars with diameters of 350 nm and densities of 2.6 × 10^8 cm^-2 were demonstrated and controlled by the thickness of Ni film and the NH3 annealing time. These GaN nanopillars show improved optical properties and strain change compared to that of GaN film before ICP etching. Such structures with large-area uniformity and high density could provide additional advantages for light emission of light-emitting diodes, quality improvement of ELO regrowth, etc.
