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• 1. [Article] The Effect of Plasma on Graphene Quality in an Inductively Couple Plasma Chemical Vapor Deposition Reactor

  Despite continued interest in research and application development, full scale graphene production is still limited by many factors including prohibitively high growth temperature requirements. Extremely ...

  Citation × Citation Citation Abstract Copy Title: The Effect of Plasma on Graphene Quality in an Inductively Couple Plasma Chemical Vapor Deposition Reactor Author: Coyne, Brendan Year: 2017 Despite continued interest in research and application development, full scale graphene production is still limited by many factors including prohibitively high growth temperature requirements. Extremely high quality graphene growth is possible at high temperatures using chemical vapor deposition (CVD). Use of an inductively coupled plasma chemical vapor deposition (ICP CVD) reactor with the benefit of precursor gas decomposition through plasma generation, may provide possibility to reduce growth temperature. Herein, we report plasma’s effects on graphene growth by comparing growths of increasing power supplied to plasma generation and changes in precursor gas ratios. Plasma composition was characterized by ultraviolet and visible light spectroscopy; graphene was characterized by Raman spectroscopy. Plasma was observed to change gradually and in a threshold shift. Gradual changes in plasma resulted in changes in graphene quality, both defect density and number of layers. The shift produced sudden changes in graphene quality. Further, increasing power before and after the shift produced opposite correlated trends. Finally, reduced hydrogen to acetylene gas ratios produced plasma associated with higher powers at a higher gas ratio. Though the comparative plasma spectra between the two reduced gas ratio growths were very similar, the quality of graphene was different. Additionally, both lower gas ratio growths produced quality different than what was expected by the trends suggested by the higher gas ratio growths. Though plasma demonstrated a role in graphene quality, a more detailed understand of its driving mechanisms must be developed in conjunction with other growth mechanisms if it is to be utilized to substantially reduce growth temperature. Title: The Effect of Plasma on Graphene Quality in an Inductively Couple Plasma Chemical Vapor Deposition Reactor Author: Coyne, Brendan Year: 2017 Despite continued interest in research and application development, full scale graphene production is still limited by many factors including prohibitively high growth temperature requirements. Extremely high quality graphene growth is possible at high temperatures using chemical vapor deposition (CVD). Use of an inductively coupled plasma chemical vapor deposition (ICP CVD) reactor with the benefit of precursor gas decomposition through plasma generation, may provide possibility to reduce growth temperature. Herein, we report plasma’s effects on graphene growth by comparing growths of increasing power supplied to plasma generation and changes in precursor gas ratios. Plasma composition was characterized by ultraviolet and visible light spectroscopy; graphene was characterized by Raman spectroscopy. Plasma was observed to change gradually and in a threshold shift. Gradual changes in plasma resulted in changes in graphene quality, both defect density and number of layers. The shift produced sudden changes in graphene quality. Further, increasing power before and after the shift produced opposite correlated trends. Finally, reduced hydrogen to acetylene gas ratios produced plasma associated with higher powers at a higher gas ratio. Though the comparative plasma spectra between the two reduced gas ratio growths were very similar, the quality of graphene was different. Additionally, both lower gas ratio growths produced quality different than what was expected by the trends suggested by the higher gas ratio growths. Though plasma demonstrated a role in graphene quality, a more detailed understand of its driving mechanisms must be developed in conjunction with other growth mechanisms if it is to be utilized to substantially reduce growth temperature. Close

• 2. [Article] ZnO Nanoneedle/H2O Solid-Liquid Heterojunction-Based Self-Powered Ultraviolet Detector

  ZnO nanoneedle arrays were grown vertically on a fluorine-doped tin oxide-coated glass by hydrothermal method at a relatively low temperature. A self-powered photoelectrochemical cell-type UV detector ...

  Citation × Citation Citation Abstract Copy Title: ZnO Nanoneedle/H2O Solid-Liquid Heterojunction-Based Self-Powered Ultraviolet Detector Author: Li, Qinghao, Wei, Lin, Xie, Yanru, Zhang, Kai, Liu, Lei, Zhu, Dapeng, Jiao, Jun, Chen, Yanxue, Yan, Shishen, Liu, Guolei, Mei, Liangmo Year: 2013 ZnO nanoneedle arrays were grown vertically on a fluorine-doped tin oxide-coated glass by hydrothermal method at a relatively low temperature. A self-powered photoelectrochemical cell-type UV detector was fabricated using the ZnO nanoneedles as the active photoanode and H2O as the electrolyte. This solid-liquid heterojunction offers an enlarged ZnO/water contact area and a direct pathway for electron transport simultaneously. By connecting this UV photodetector to an ammeter, the intensity of UV light can be quantified using the output short-circuit photocurrent without a power source. High photosensitivity, excellent spectral selectivity, and fast photoresponse at zero bias are observed in this UV detector. The self-powered behavior can be well explained by the formation of a space charge layer near the interface of the solid-liquid heterojunction, which results in a built-in potential and makes the solid-liquid heterojunction work in photovoltaic mode. Title: ZnO Nanoneedle/H2O Solid-Liquid Heterojunction-Based Self-Powered Ultraviolet Detector Author: Li, Qinghao, Wei, Lin, Xie, Yanru, Zhang, Kai, Liu, Lei, Zhu, Dapeng, Jiao, Jun, Chen, Yanxue, Yan, Shishen, Liu, Guolei, Mei, Liangmo Year: 2013 ZnO nanoneedle arrays were grown vertically on a fluorine-doped tin oxide-coated glass by hydrothermal method at a relatively low temperature. A self-powered photoelectrochemical cell-type UV detector was fabricated using the ZnO nanoneedles as the active photoanode and H2O as the electrolyte. This solid-liquid heterojunction offers an enlarged ZnO/water contact area and a direct pathway for electron transport simultaneously. By connecting this UV photodetector to an ammeter, the intensity of UV light can be quantified using the output short-circuit photocurrent without a power source. High photosensitivity, excellent spectral selectivity, and fast photoresponse at zero bias are observed in this UV detector. The self-powered behavior can be well explained by the formation of a space charge layer near the interface of the solid-liquid heterojunction, which results in a built-in potential and makes the solid-liquid heterojunction work in photovoltaic mode. Close