tailieunhanh - Báo cáo hóa học: " Giant Persistent Photoconductivity of the WO3 Nanowires in Vacuum Condition"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Giant Persistent Photoconductivity of the WO3 Nanowires in Vacuum Condition | Huang and Zhang Nanoscale Res Lett 2011 6 52 http content 6 1 52 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Giant Persistent Photoconductivity of the WO3 Nanowires in Vacuum Condition Kai Huang Qing Zhang Abstract A giant persistent photoconductivity PPC phenomenon has been observed in vacuum condition based on a single WO3 nanowire and presents some interesting results in the experiments. With the decay time lasting for 1 X 104 s no obvious current change can be found in vacuum and a decreasing current can be only observed in air condition. When the WO3 nanowires were coated with 200 nm SiO2 layer the photoresponse almost disappeared. And the high bias and high electric field effect could not reduce the current in vacuum condition. These results show that the photoconductivity of WO3 nanowires is mainly related to the oxygen adsorption and desorption and the semiconductor photoconductivity properties are very weak. The giant PPC effect in vacuum condition was caused by the absence of oxygen molecular. And the thermal effect combining with oxygen re-adsorption can reduce the intensity of PPC. Introduction One-dimensional 1D nanotubes nanowires or nanorods have shown much higher sensitivity than bulk materials at room temperature because of their higher surface-to-volume ratio and stronger dependence of electrical conductance on the amount of adsorbates 1-5 . Their optical and electrical characterization is a direct way to gain a deep comprehension of some of novel phenomena of the nanostructure that originate from the overexposure of the bulk of nanomaterials to surface effects. Recently the persistent photoconductivity PPC effect has been observed in ZnO nanowire 6 n-type GaN thin film 7 and rough Si nanomembranes 8 . Persistent photoconductivity which means that photoconductivity p ersists after the illumination has ceased and hindered the quick recovery of the initial unperturbed state implies .